Author's note: If you search Literotica for "X-Change" (with a hyphen) stories, the search engine returns only "xchange" without the hyphen. To find story titles that have the hyphen, you must search "x change" with a space. Until Literotica has fixed this glitch, I have titled this story so that it can be more easily found under any alternate spelling.

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"Good morning class, I am Dr. Brewer, Chair of the Department of Human Sexuality, and I am pleased to welcome you to the 'X-Change Seminar.' Comstock Institute is proud to be the first university to offer this intensive seminar on puberty. Here you will learn, as nowhere else, what changes your bodies went through when you experienced puberty. We do that by observing two persons undergo these same changes through the benefit of the newly developed X-Change pills. This seminar is an introductory, required prerequisite for your degree in Human Sexuality. Today you will watch as a young couple has sexual intercourse—that is, they will fuck each other. Then they will each take an X-Change pill. The guy will become a girl and the girl a guy. You will watch and take notes over the course of an hour as you closely observe the changes their bodies go through. Then after they have changed, they will fuck again. If you are not comfortable watching all this, then you are in the wrong degree program and you should leave. Also, we use common words—street language. We don't say vagina, we say pussy. Instead of penis, we say cock. Those are the words that most of you use in conversations outside the classroom, so those are the words we use here. If this language makes you uncomfortable, see the registrar about changing your major. Each one of you has a different level of sexual experience before coming to this seminar, so it will be taught on the most basic level so as not to leave anyone out."

Dr. Brewer was a thirty-something gentleman dressed casually. His classes were immensely popular with the Comstock students. They appreciated his relaxed, matter-of-fact approach to teaching human sexuality to first year university students as they learned about puberty. His manner put them at ease and made them all comfortable with their mushrooming sexual interests. Everyone was anxious to begin.

"OK, class, let's begin. Standing here with me are our volunteer demonstrators: Jamie and Chris Kelly. Jamie, please tell us about yourself."

"Well, there's not much to tell. I graduated last spring from Comstock with my degree in Human Sexuality. I attended one of your first seminars with Chris and we both got a good understanding about puberty and fucking, and we've been fucking ever since, half the time as male-female, and half the time as female-male."

"Chris, tell us about you."

"Well, I guess Jamie said it all. We were in this seminar together. In fact, this is where we first met. What we learned here really explained what had happened to us in puberty, and why we were so horny all the time. So we took what we learned and practiced at as homework. We've been together ever since and loving it."

"Jamie, how would you describe your relationship with Chris?"

"She's my POSSSLQ."

A voice from the back of the classroom called out, "What's a POSSSLQ?"

"That's a Person of the Opposite Sex Sharing the Same Living Quarters."

"Chris, how would you describe your relationship with Jamie?"

"That's easy . . . I'm his cum bucket, except when we switch and then he's my cum bucket. When he's male, he produces a ton of cum every day and he wants to shoot it all into me and I want to get 'shot.' In fact, we have a little competition between us. His job is to keep his balls full, and my job is to keep them empty."

"Who is winning?" asked Dr. Brewer.

"I think we both are. This is a competition with no losers!"

"Jamie, you referred to Chris as 'she,' and she refers to you as 'he,' but it isn't always that way is it?"

"No, not at all. We've been volunteering to be the test subjects for this seminar every 3 months. This will be our twelfth switch . . . or is it thirteenth? I've kinda lost count. Whatever we switch to, we stay that same sex for three months until the next time you offer this seminar. We get to experience the best of both worlds."

"I forget," mused Mr. Brewer, "Which of you was male before you started switching?"

Jamie and Chris looked at each other, both with a puzzled expression on their faces. After a short pause, Jamie suggested, "I think it was me, wasn't it Chris?"

"Maybe," Chris answered with uncertainty in her voice. "It sounds right, but I'm not certain. Maybe we have some old photos that would tell for sure."

"Your uncertainty makes me wonder if the frequent switching makes for confusion in your lives in other ways, too?" asked Mr. Brewer.

"It did at first, but not since we got driving licenses with two photos on each: one as male and one as female. And we both have names that are gender neutral: Jamie and Chris. It helps that we both got jobs working for Congressman Johnson. He wholeheartedly supports the X-Change Program, and is one of the vocal sponsors of your seminars. He was also very helpful in getting us the special driving licenses. He's preparing legislation to make it possible for other X-Changers to also get a dual-sex license with two photos. So, whichever sex we happen to be at the moment is OK, even if we don't remember what we started out as."

"Please tell us why you volunteered to become repeat demonstrators for this quarterly seminar. Jamie, you start."

"Like I said, this class was such a big help to me a few years ago. It got me through my constant horniness with no hang ups. It was a huge turn on to see that couple fucking and to watch how their bodies changed when they took X-Change pills. They helped me to get over any embarrassment about fucking the first time. So I wanted to help others the same way. Chris and I met in class and talked about it, and when the class ended, we couldn't wait to go somewhere and fuck."

"Chris, how about you?"

"I agree with Jamie. Sex should be open and natural not hidden away like a secret. Everyone does it so why can't we be more casual about it? This class helped me to develop the right attitude and now Jamie and I have a great sex life. If fucking was an Olympic event, I think we might get a medal. Also, from the first time we saw them, we have been curious about the X-Change pills, and by volunteering to be demonstrators for your seminars we get to use them four times a year for free."

"What positive benefits have you found from X-Change pills?"

"Well, I love how I feel with Jamie's cock in me. It feels me up, and my pussy feels RIGHT. You know what I mean? Pussies are made to be filled with a cock, and when mine is full with Jamie's cock, it feels like it was meant to be. But, even though I love that feeling, I always wondered what it would feel like to be male and to have a cock and feel it inside a pussy. Now I know. As a male, I really love having my cock inside a female Jamie and shooting my load into him . . . . I mean her. . . . Sorry about that; we're always getting mixed up on pronouns, especially right after a change."

"Curiosity is the most common reason people give for trying X-Change."

"Jamie, how about you?"

"Yes, I was curious, too. When I was balls deep in Chris, there was no place I would rather be. And when I would shoot my load into her pussy I would often wonder what it feels like for her to have hot spunk shooting in. Now I know. I love it both ways."

"You two would make great sales reps for X-Change pills, but we're not here to sell the pills. In fact, the pills we use are not the typical kind. You see, regular X-Change pills work very quickly, and the change is complete in a matter of minutes. But, for our seminar, X-Change makes a special, slow-acting blend so that we can watch the change happening slowly and discuss it as it happens for educational purposes. You see, class, X-Change works by taking a person's body back to an earlier stage of development. When a baby is in the womb and is just a few cells it has no specific sex. Only as it grows do the cells begin to be either male or female. X-Change reverses some of your cells to that early stage and then chooses the opposite path. Then on the new path, it moves you forward again through the steps of puberty, but as the opposite sex. Seeing the changes happen slowly gives us all time to ask questions and understand. But, whereas typical puberty happens over a span of years, the pubertal changes you will see here today happen over about an hour. . . . Class, any questions?"

"When are they going to fuck?"

"Right now. Jamie and Chris, your audience is ready; are you?"

"I thought you'd never ask!" And with that they both quickly stripped down.

Jamie was medium tall, about five eleven with neatly trimmed brown hair. He had a patch of hair on his sculpted chest and a light dusting of fine hairs on his arms and legs, but his pubes were cleanly shaved. He was quite handsome and had just a hint of a moustache. At 165 pounds, his body was perfect for his height.

Chris was much shorter than Jamie, but not petite. At five five and 130 pounds, she was also just right. Her blond hair and blue eyes were the envy of every girl who saw her as were her 36D breasts. She shaved her pussy, but left a blond landing strip for a highlight. As she undressed, the boys present watched approvingly.

Jamie was the first one done and as he lowered his boxers, his rock hard shaft sprang up and bounced off his abdomen.

"Jamie, I see you're ready. I also notice that you are not circumcised. Class, circumcision means that the foreskin of a male's cock was cut off by a doctor, probably when he was a newborn. Fortunately, that barbaric practice of mutilating a man's cock without his knowledge or permission is dying out. The reasons given by its proponents are nothing more than lame excuses. One of the blessings of the X-Change process is that when any person changes into a man, he will be whole because his DNA produces a foreskin and he will be reconstituted according to the blueprint in his DNA." As Mr. Brewer shared these facts about circumcision, he demonstrated by holding up Jamie's cock and moving the foreskin off and back onto his cock head several times.

Better stop that," cautioned Jamie, "I don't want to cum until I get inside Chris."

"I understand," said Mr. Brewer as he removed his hand. "But I saw a teaching moment and took advantage of it."

"No problem. . . . You know, I used to be circumcised. But then through X-Change I became female Jamie for three months, then when I reverted to male Jamie, it gave me back my uncut cock the way I am supposed to be."

"It's much the same with me," said Chris. "Every time I change from a male back into a female

Chris, I become a virgin again, or at least I get my hymen back. I guess technically I'm not a virgin, even though I have a new hymen. It's there in my DNA and that's the blueprint the X-Change pill follows when it rebuilds my body."

"I notice that you both have shaved off your pubic hair. But every time you change, you get it back, don't you. And if either of you have tattoos or piercings, you will lose them also, because they are not part of your DNA. . . . Jamie, how long is your cock?"

"I'm about average, 6½ inches hard."

"And he's always hard," quipped Chris.

"Well, she exaggerates a little, but I admit, she keeps me hard a lot of the time."

"Chris, I see you're ready, too. Your nipples are standing up like little soldiers, and if I'm not mistaken, I think I see plenty of moisture on your pussy lips."

"Oh, yes, I am so-o-o-o-o wet," she said, running her hand through her slit to bring it back up dripping wet. "Just thinking about fucking for an audience has kept me wet since I woke up this morning. And I am still wet from Jamie's morning cum, too."

"So this is your second fuck for the day?"

"Yes, two down and who-knows-how-many-more to go."

"Well, we know for sure that this will be your second fuck today as a woman, and the third fuck, in about an hour, will be as a man."

"Let's go! I'm ready. Jamie, fuck me now! No foreplay needed. Straight missionary."

The front of the classroom had the teacher's desk pushed off into a corner and in its place were two beds, separated so there was plenty of space around each one. This was to enable the students to gather around and observe all activity closely. Chris quickly went to one of the beds and lay back. In a flash, Jamie was on top of her and sunk his cock deeply into her pussy until his balls slapped against her pert rounded ass.

"Class, gather around the bed. Bring your notebooks and pens and record your impressions about what you are seeing. If there is anything you don't understand, make a note of it and we will discuss it later."

Jamie moaned as Chris' tight little pussy caressed his throbbing erection with its hot and slippery interior. Jamie did not try to hold back at all. His primary goal for this day was to experience X-Change again, and this fucking was just a necessary step he had to get out of the way. He knew for a fact that Chris felt the same way. He stroked in and out purposefully, going balls deep on each in-stroke. Sometimes he would grind for a few seconds at the bottom of each stroke, thoroughly enjoying the feeling her snuggly gripping hole would send to his brain through the nerves in his engorged member. But even as he enjoyed his mounting excitement, his brain was already reliving and anticipating the pleasures of being on the receiving end of his next fuck when Chris' cock would be invading his own hot pussy.

He knew that Chris was getting close when she wrapped her silky smooth thighs around him and with her feet pulled him into her faster and harder.

Like Jamie, Chris was also moaning. She daily practiced her Kegel exercises so that her tightly gripping pussy was able to stimulate Jamie's massively swollen cock for a fast orgasm for both. Normally, they liked to take their time. With control, they could make their love-making last and last. But today was different. This male-female fuck was just for the benefit of these students, many of whom were virgins. So the goal was to cum quickly and then get the X-Change pills so they could fuck again, only this time as female-male.

Chris sometimes wondered if she and Jamie were exhibitionists. They both enjoyed having an audience while they fucked, and they especially enjoyed having spectators while they went through the change. But it was just an idle thought, because whether it was true or not didn't matter. That's just the way they were, and being X-Change demonstrators gave them the perfect way to live out their fantasy.

Before long, Jamie felt his little head swell up and throb as the boiling sensation deep in his balls began and he knew his orgasm was imminent.

"I'm almost there," he said to Chris.

"Yes, I felt it too," she spat out between her ragged breaths. "Go ahead and shoot; I'm ready to cum, too."

And they did. Jamie shot rope after rope of hot, white cum into her, groaning loudly with each spasm as her pussy convulsed around him.

"OK, guys, that was really great," said Dr. Brewer as the students applauded. "Class, what you just saw was a quickie. A quickie is just what it says—it is a fuck done in a hurry. You might do it if time is short or for other reasons. In this case, they did it because both were highly aroused and so they didn't need any further arousal which is the main reason for foreplay. But foreplay is usually very important and it is a part of what you will be instructed in today. After they complete the transformation of the X-Change pills, then they will need to arouse each other with foreplay in preparation for their first fuck today as the opposite sex. Jamie will even have a hymen—a cherry—that Chris will have to break with her—or rather his—new, uncircumcised cock. Any questions? . . . . Yes, in the back."

"When are they going to change?"

"Very soon. So, here's how we will proceed. This class is about equally divided between males and females. The males will gather around this bed where female Chris will change. You will take measurements and record your observations after she swallows her X-Change pill. Specifically, you will measure her chest size using this tape measure. Measure her every five minutes and record the changes. Chris and Jamie have given permission for you to touch them in order to make the necessary measurements, and sometimes they will even ask you to stimulate them. Additionally, you will measure her clitoris every five minutes as it becomes a cock and record those changes as well. Carefully observe her body and write down any changes you see taking place. Watch as her inner pussy lips balloon out as her ovaries (which have become testes) descend and change those lips grow together and become her. . . I mean his. . . scrotum. Carefully watch as her pussy/vagina closes up and disappears and how her urethra (piss tube) elongates and attaches to the bottom of her growing cock. Unfortunately, you won't be able to witness the interior changes, but they are remarkable. Her entire bone structure will change causing her hips to narrow. Her uterus will change and become her new prostate. She will grow taller, so you will need to measure her height every five minutes. Pay attention to her nipples and areolae, the brown area surrounding her nipple, and record the changes you see happening there. Watch for body hair that will be appropriate for her new male body. . . . Chris, anything you want to add?"

"Just to say that I will be guiding these fellows through the process as I become one of them. As I feel significant changes taking place, I will point that out to them so they don't miss anything. So, if you want to take the girls over there to the other bed to fill them in on what they are to expect as Jamie changes, I'll swallow this pill and get started here."

"Sounds like a good plan."

CHRIS' STORY.

"OK, guys look at the clock and record the time I am swallowing this pill. You, what's your name?"

"Paul."

"OK, Paul you are timekeeper. Let us know every five minutes so we can update the measurements. Now take all your first measurements. First, let me get on this scale. . . ."

"It weighs me and you can also measure my height. . . ."

"Write that down. . . ."

"Now, you, what's your name?"

"John."

"OK, John, grab that tape and measure my chest. . . . First, measure under my breasts. . . . Yes, just like that. Write it down. Now, make a second measurement across my breasts. . . . Good. Write it down."

"You . . . ."

"Phil."

"Phil, come close and look very carefully at my nipples and areolae and write down what you see. . . . Use that tape and measure the length of my nipples, and the diameter of my areolae. . . . No, no, make the nipples hard first. Lick them and suck on them. Don't be shy; that's what you're here to do. . . . Much better. . . . Now write down the measurements."

"You. . . ."

"Fred."

"Fred, you see those calipers on the teacher's desk? . . . Go get them. . . . Get down between my legs. . . . That's right, come in close. . . . Now lick my clit to make it hard. . . . That's OK. Everybody has a first time. . . . Take your time. . . . That's nice. . . . Keep doing that; that feels great. . . . Oh, yes, Fred, you're a natural at this. . . . Yes-s-s-s-s. . . . OK, that should do it. Now take the calipers and gently measure my clit and write the number down."

"Time," said Paul the timekeeper.

"Great timing. Now you need to take all the measurements again. Everyone take a turn. Everybody gets to try everything."

40 minutes later, Sam was about to take his turn measuring Chris' clit.

"Chris, I don't mind measuring your clit, but I can't lick it. It looks too much like a cock and I'm not gay."
"No problem Sam. In fact, you need to show in your notes that at 40 minutes, I appear to you to be more male than female. Record that along with the fact that my areolae are smaller and lighter in color, my nipples smaller, my inner pussy lips have grown together and they are starting to fill up with my new balls. Be sure to mention the hair on my chest, arms and legs, some beard starting to show, and have you noticed that my voice is changing and is much deeper. With my greater height and narrower hips, I am becoming one of you guys and I am starting to get horny as hell. . . . Any questions?"

"What did it feel like? Did it hurt?"

"It starts with an all-over tingling. It is actually quite pleasant. I have never taken regular X-Change pills, so I'm not sure what they feel like. I only know that they work much faster. These slow-acting ones are specially made for this seminar, and they are a very enjoyable experience. Inside I can feel things sort-of moving. I guess some things are growing and other things shrinking. Some bones are getting longer, especially in my legs, and my hip sockets are changing as my pelvis shrinks and changes shape."

"We could actually see your breasts moving or shrinking."

"Yes, I could feel it. There is kind of a sucking feeling in my breasts as they shrink and draw in to my chest. Slowly I lose feeling in my nipples. As a woman they are much more sensitive than when I am male. There is a really neat tickling sensation in my clit as it elongates and becomes a cock, especially when you guys were licking it to take your measurements. We can't see inside, but they tell me that my ovaries shrink down to almost nothing and then they will begin to grow again as testes - balls, and then they will start to push down and into the skin of my inner pussy lips. Then you saw as my pussy lips grew together and my pussy closed up and formed a scrotum with the raphe line down the middle."

"Your clit really grew fast!"

"Yes, I am not surprised. In a few more minutes, my clit will become a 7½ uncut cock. It is always the same because that's what is in my DNA. Jamie loves me to fuck him . . . . I mean her, with it, and I love doing it. But, I also love when male Jamie fucks me with his 6½ inch cock. That inch makes no difference. You saw how hard he made me cum a while ago."

"Which do you like better: being male or being female?"

"Wow, that is a really tough question. When it comes to sex, each has its benefits. One drawback of being female is monthly periods. One drawback to being male is those unpredictable hardons that pop up at the most embarrassing times. An advantage of being female is the passive side of sex. Women don't have to worry about getting and staying hard. An advantage of being male is the way testosterone boosts your libido. It feels good to be horny! . . . . So, what surprised you most?"

"Definitely your face. You were gorgeous a few minutes ago, but now your chin is getting wider, and whiskers are starting to grow on your cheeks. You really ARE turning into a guy."

"That's the whole idea, and in a few more minutes I am going to fuck Jamie until she screams for me to stop!"

"Hey! I heard that!" said Jamie.

JAMIE'S STORY

"How are you doing over there, Babe?"

"Well, they tell me that my cock is shrinking really fast. The first time that scared the shit out of me, but now I know it's just turning into a clit for you to suck on."

"Has your vagina started to form yet?"

"Yes, these guys just told me that they have noticed a dimple forming there that is deepening as they watch."

"Be sure to make it good and deep so I have a nice warm, slippery place to put my 7½ inch cock."

"I will, and I can hardly wait. That's the bad part about these slow-acting pills. The regular ones would work in less than five minutes."

"That's true," said Dr. Brewer, "But the changes would happen too fast and all at once so that it wouldn't serve as good a lesson for these students. So much is happening that they need to observe the changes slowly."

"I know. I understand that. It's just that it's a little frustrating to wait. I've been male for the past three months, and now I'm really looking forward to three months as a female and I want to get laid NOW!"

"Like I said, you two are great salesmen for X-Change pills. I think every student who has participated in your seminars has given them a try, and so far, no complaints."

"I can see your breasts growing!"

"What's your name, honey?"

"Mary Jane."

"Well, Mary Jane, I'll have you know that they will keep growing until they are 36D's."

"Wow! Cool!"

"And your scrotum looks like a balloon that is losing its air; can I touch it?"

"Sure. Just be gentle. And I can feel it drawing in and shrinking. My balls are shrinking and drawing up into my body. And if you watch closely, you see that line that goes down the center of my balls and across my taint right to my asshole? Dr. Brewer, point it out to them, please. . . . . Well watch as that line, which is called the raphe, opens up and each half of my former scrotum becomes one of the inner lips of my soon-to-be pussy. And right in front of my asshole, that dimple that you saw will continue to get deeper until it becomes the hottest, slipperiest, most desirable pussy you ever saw."

"Hey Jamie, you're really cute. Your face has totally changed and you're getting a model's body with great breasts, wide hips. You were handsome as a guy, but as a girl you are a real babe! Everything is just about perfect."

*****

"The hour is up," announced Dr. Brewer. "All students take your final set of measurements. And Chris, as soon as they are done, feel free to fuck Jamie until she squeals to everyone's delight."

"Jamie, come here, Sweetheart."

"It feels funny looking up at you. For the past three months, you had to look up at me."

"Enough talk. Just kiss me."

Chris took Jamie into his arms, and gently pressed his lips against hers. Then harder. Then they both opened their lips and their tongues battled for control.

"What's that?" asked Jamie. "Are you THAT horny? I feel someone down there already reacting."

"Your kisses could raise the dead."

"Let's get comfortable." And with that they lay down upon the bed. Chris began again at Jamie's lips, then slowly kissed his way along her jaw and back to her ear, kissing softly and tonguing her ear. Then down to her neck.

"Oh, you know how I love my neck kissed. When I was male, that didn't appeal to me."

Chris said nothing but just continued his gentle kissing and tonguing as he worked his way down to her 36D's. There he gently kissed around each nipple and sucked them one by one, causing Jamie to moan.

"Oh, that makes me so horny and wet."

To confirm, Chris reached his hand down to her pussy.

"Oh!" he suddenly said.

"What's the matter?"

"Hair. I just forgot for a minute and it startled me. No problem." And with that he parted the hair and her lips and confirmed there was ample moisture.

"Babe, you are really wet. I guess you're as horny as me. It's hard to believe that just over an hour ago we fucked like rabbits and YOU came in ME. Now I get to return the favor."

"Yes, Chris. Fill me with your hot, creamy cum. Stick that huge cock of yours into my hot, wet love tunnel and fuck me silly."

"I love it when you talk dirty!"

"I know. That's why I do it. And I love it when you eat me."

Chris moved down between Jamie's legs and used both hands to move her ample brown hair back from her pussy lips.

"When we get home, we're shaving."

"Deal. I'll shave you if you shave me."

"Deal."

Chris inhaled a deep breath. "You smell just as good as I remembered you." Then he pushed his mouth onto her deliciously tight pussy covering her completely and running his tongue up and down her slit. "And you taste great, too!" Jamie moaned approvingly, then as Chris inserted his tongue in her vagina, she arched her back and cried out.

"Suck my clit. Make me cum."

Chris focused all his attention to her clit. In the back of his mind, he thought how just an hour ago, this little clit was a 6½ inch cock. The first time that happened, it made him pause for half a second, but it no longer bothered him and he sucked with genuine glee. It was only a couple of minutes before Jamie was cumming hard, arching her back and pushing her pussy hard against Chris' face, even reaching down and holding the back of his head to increase the pressure.

"WOW! That's what I call foreplay," said one of the students watching.

Dr. Brewer sensed another teachable moment so he added, "All their senses are brand new. All physical touch is at its peak. There is no dulling of the senses as can happen in the normal aging process. So, what they are feeling is maximum pleasure from organs designed specifically for pleasure."

"Over on your back," said Jamie to Chris. "Let's see if this body remembers how to deep throat." She dropped down and immediately took his semi-hard cock into her mouth, causing a grateful moan from Chris. She licked the underside of his tool with her tongue while stroking him in and out. Then she took it out and ran her tongue around the rim of the helmet-like head. Quickly he got rock hard from this attention, and Jamie positioned herself to deep throat. She took in most of him before triggering her gag reflex. Then took him out to say, "Just give me a minute to get used to it again." Then she thrust her head down almost to that point, then paused while she relaxed her throat. Then she took a deep breath through her nose, opened her mouth as wide as possible, stuck out her tongue as far as possible and pushed his cock right to the back of her throat. But she still had 1½ inches to go. Pushing hard she reached her goal, and licked Chris' balls with her tongue, smiling inwardly at her success.

Jamie held him there as long as her breath allowed and then pulled back, breathing deeply to regain her air before going deep throat again. This time she didn't hold him in but stroked him with her throat, making four inch strokes. Jamie knew this was Chris' favorite oral sex and would soon cum. He didn't disappoint and soon shot his first load of cum (that is, first load on this cycle), shot it down her throat. As soon as he finished, Jamie immediately came up for air.

"Jamie, you're the greatest. Without a doubt you are the world's best cocksucker," said Chris. "I don't know how you can hold your breath for so long."

"I want to know how you keep from choking," said one of the students watching.

"Partly that comes from practice, and partly it comes from relaxing my throat and sticking out my tongue as far as I can. It seems to minimize my gag reflex. I don't know if that works for everyone, but it works for me, and it really gets Chris off. He does much the same thing on me when he's a female and I'm male. Regardless of the length of the cock, you do it the same way. . . . Any other questions?"

"Yes, are you going to fuck? Or is a blowjob the whole show?"

"Oh, we are definitely going to fuck," said Chris. "I just need a moment to recover. I think Dr. Brewer calls it the refractory period."

"Yes, that's correct. It varies from male to male. Anything from five minutes to overnight is normal. How long do you usually need to recover, Chris?"

"Ten to fifteen minutes usually seems to work for me," answered Chris. "Any other questions?"

"Will you do the missionary position again?"

"No, in order to give you some variety, we'll do some cowgirl, reverse cowgirl, doggie, and standing doggie. The handouts that Dr. Brewer gave you should have drawings of those positions and dozens of other ones, so you should be familiar with them."

That seemed to be a popular idea with those students who were still paying attention. About half the group, however, had already paired up and moved a short way away from the group and seemed engaged in heavy conversation. Chris and Jamie noticed this fact and glanced at each other and smiled. They obviously remembered meeting each other the same way.

Chris leaned in to Jamie and whispered in her ear, "I wonder how many of them will become X-Change demonstrators like us."

Ten minutes later, Chris said, "Jamie, are you ready to go again? I think I am."

"Sure am! Can I start on top in reverse cowgirl? I love to play with your balls in that position."

Chris lay flat on his back and Jamie knelt over him in a 69 position and quickly sucked him hard. Just as quickly, he licked her slit and started her ample juices flowing. Then she crawled forward until her pussy was suspended over his throbbing erection. She rubbed the head back and forth in her slit to coat it with her slippery juices and then slowly lowered herself onto his eagerly awaiting rod. She slowly slid down its entire length, easily popping her cherry, until her pussy lips flattened out on Chris' pubes caressing his rod with the warm embrace of her inner folds. For a few seconds she held her position and ground her hips in small circles, eliciting moans from Chris as she pulled up on his swollen balls to rub them against her clit.

"Oh, Jamie, you do me so good," breathed Chris.

After a few minutes, Jamie carefully turned around, pivoting herself on Chris' pubes so that his turgid member stayed in her honey tunnel. Chris preferred this position as it gave him access to her firm rack. He spent several minutes pulling and twisting her soft pink nipples which had hardened and were pointing upwards. He amused himself by pushing down on them and releasing to watch them spring back upward like spring steel. Occasionally he would raise his upper body with his arms extended behind himself and nibble and suck on her silky smooth tit flesh.

But soon they spoke together and said, "Let's do doggy." Having the same thought at the same time made them both laugh as Jamie lifted off Chris' still throbbing pole and knelt beside him on the bed. In no time he got behind her and slid in to the hilt. Then, looking to the students he said, "Doggy has many advantages. Jamie can reach back with one hand and play with her clit while I fuck her. It also lets me lean forward and play with both her breasts and tweak both nipples. Doggy lets my cock go deeper into her and it lets me stroke her G-spot more easily. And if you're trying to get pregnant—which we're not—it lets my cum stay in better and make conception more likely. . . .Any questions?"

"You say you're not trying to get pregnant, but you're not using a condom."

"Another advantage of X-Change is that it prevents pregnancy for six months after a change. And since we change every three months, we're protected. If and when we decide to start a family, we will have to decide who will be the mom and who will be the dad. Then we'll have to stay in that arrangement for at least six months to get pregnant, and then nine more for the pregnancy itself. Then another three to six months or more for nursing the baby. So, starting a family means no changes for a couple of years."

"Which do you want to be—mother or father?"

"Actually, both. One of us will go first to be the mother, then after a couple of years, we will change and then the other one will be the mother. That way we will both get to experience carrying and birthing a baby. . . . Now, if there are no more questions, I am close to cumming and I want to shoot my load in a standing doggy position."

Saying that, he pulled out as Jamie climbed off the bed and went to the teacher's desk and leaned across it, presenting her pert ass with its taut muscles to him. He immediately sunk in and began stroking with a deliberate goal in mind. Holding Jamie by the bend in her hips he pounded harder and harder, faster and faster. As before they both came simultaneously to an appreciative round of applause from the students.

As the applause died down, Dr. Brewer motioned for quiet so he could speak. "OK class," he said. "Last chance for any questions."

Several hands went up all at once. Choosing the closest one, "Do you have any more of those pills? I would like to try one." A chorus of voices indicated that they all had the same question.

"Sorry. They only give me two pills every three months. Just enough for the seminar demonstrators. But don't give up hope. They have informed me that they want to start additional X-Change seminars in several other parts of the state, and in a few months they will expand to other states as well. And so they are going to need many seminar graduates to volunteer to be seminar demonstrators. If you are interested, sign up here."

Dr. Brewer barely got out of the way of the stampede of seminar students who surged forward to sign.

"Don't forget, in two weeks you all must submit a report on what you have learned here today. 10 pages, double spaced."

But no one was paying him any attention.