My Job as a Model Patient Pt. 03

The school term went on and on. Twice a week, I'd go to the college and have the masked medical students feel my balls, play with my dick and take turns sticking their fingers up my ass until I came. And once a week, I'd lie back on the examination table as they held down my arms and spread my legs while they milked me with a transparent fleshlight taking notes and watching me come. Weird how routine it became.

And even with my sister, Lisa (otherwise known as L.), not realizing I was the masked model patient, it became routine as well. When she was in my class, she'd happily grab the base of my dick and hold me in place while that fleshlight was milking on me. And on the rare occasion the professor stepped out of the room, she'd give me a quick playful suck or lick - much to the laughter and thrill of her classmates. By dinner, my sister would be telling our parents about the 'cute skinny virgin guy' in her lab. Of course she didn't tell them how hands-on (or mouth-on) she was!

I said nothing. As far as my parents and sister knew, I was the unemployed loser who stayed at home or at a friend's playing video games non-stop. No one noticed that I was buying new game consoles or video games with my 'hard' earned cash! And at what point do you tell your family that your sister has been playing with your dick?

But her opinion did matter to me. I once asked my sister if she thought the model patient had a nice penis or not. Her reply? "Why do you want to know, Aaron? You are such a perv! I'll tell mom and dad that you're gay!"

Finally, the last day of class was here. It was the big D day. Demonstration Day. Professor Apple expected me to have actual sex with a female volunteer in front of the class. And that volunteer was none other than my sister, L!

This I worried about. I mean, for $500 would you have sex with your sister? Even when it's anonymous - we'd be wearing our surgical masks, but *I* would know it's her. Don't get me wrong - my sister is pretty - she's a blonde with perky tits but she was always a bitch to me. She liked to kick me around when we were kids. She liked to call me Skinny Monkey. And she, with her line of boyfriends from the football and swimming teams, was always outgoing and loud. She might laugh at my clumsy attempt to "copulate" as the Professor would say.

D-Day. Demonstration Day. What can I say? $500 is $500.

I walk into the lab, showered and masked to meet up with Professor Apple. He's smiling as usual. I actually think he's the perv, watching me cum every day. But there's my sister, L., with her mask on as well and her blonde hair up in a bun. Like me, she's got her lab coat on and nothing underneath - ok, that's a hot look. We're getting our instructions from the Professor.

"Thank you, my volunteers. Today, you two will perform coitus in front of the students. I know the model patient fee of $500 helps, but I realize I'm asking you two to perform an intimate act with an audience of strangers. The purpose of this class is to show human reproductive biology in real time. This class is only an hour long, and with instructions, we will only have time for a couple positions, but I want the class to see actual copulation."

L. nods enthusiastically. I say nothing but quietly take the viagra the professor hands to me.

"You both with be wired up with micro-cameras. This is a historic day for the college! Very few institutions have footage of intercourse from within the vagina! You both have been tested for STD's. Our female volunteer is on the pill - so there will be no condom. We will have an unfettered view of your genitalia."

Holy shit, how fucked up would that be if I knocked up my sister? I shudder but the professor is droning on.

"Now young man, please follow my instructions carefully. This is not for you to get your rocks off! This is an educational study, so when I ask you to move in a certain way, you do so. When I tell you to stop, you stop. When I tell you to go, you go. Understand?"

I nod.

"Good! The same goes with you, young lady. You are posing to show off entry points and organs to the class - this is not an actual bout of sex. You were telling me about your yoga and Pilates classes - it's going to be like that - lots of posturing to show how his organ is penetrating you."

My sister, the over-achiever, nods quickly. "I'll show him the ropes," she says. I had no idea she took yoga and Pilates. The professor leads my sister to the examination table to lie on her back naked. Her perky tits actually look bigger and floppier lying down without her bra on. I had no idea her nipples would be so big. The professor is whistling as he inserts the tiny camera set up into her well-honed vagina. If the school rumors were true, it was wide enough to accommodate some double penetration action.

Then the professor turns around and smiles as I stand there with my waving erection. I'm nervous. I've got goosebumps on my arms, thinking about losing my virginity, fucking in public, in front of an audience, and with my sister - holy shit, I'm going to hell. Thank goodness for viagra and $500, I think, as the professor tapes a wire to my shaft so that the endoscopic camera is just underneath my dick head. He pulls back my foreskin in case it rolls into the camera.

"It'll be ok," my sister strokes my arm.

At that, the class walks in. This time, it's all the different sections together, so we have a crowd of 12 students smirking and filing in. I'm nervous as fuck, but the viagra is keeping me hard. Looks like 4 guys, 8 girls. At the sight of my boner, the girls are giggling while the guys are muttering to each other, "yeah! Fuck yeah! This will be awesome!"

"Quiet, class! Quiet!" The professor had the group surround the examination table. "We have on the table, our female volunteer - let's call her YOUNG LADY. And standing here, obviously ready (the guys cheered) is our young male volunteer - let's call him YOUNG MAN. Today's final class, we will be observing coitus. Both are wired with cameras so we can record and observe there (he points to the monitors) but it is important that you all watch closely and learn about human reproductive systems. Depending on class time, we will do only a couple positions (awwwww) which will culminate in ejaculation. With any luck, the cameras will capture this very amazing act!

Everyone have their gloves on? Good! First thing, we are VERY lucky because our female subject has very strong vaginal walls. Thanks to her regimen of yoga, Pilates and kegel exercises and... much use.. (the class laughs), she has full control over her vaginal walls. I want everyone to take a turn and insert 2 fingers to let her demonstrate."

The first couple guys look amazed when they stuck their fingers into L.'s pussy. She giggles and inhales deeply as she grips their fingers with her already moist pussy. "Holy shit!" one guy said, "it's like a hand shake! It's like a fist grabbing onto you!" Even the girls looked wide-eyed surprised as they one by one inserted their fingers.

"Dude!" One guy said to me, "You are lucky! A snapping pussy!" My face goes red.

The professor points to me, "All right, young man, why don't you climb up on the table?" I hop up and kneel at the foot of the table, my sister lying before me, her shaved pussy spread. She makes her pussy scrunch up and relax, so I think I'm looking at the churning pink mouth of an octopus!

"You will notice of course that our young man is fully erect with the assistance of viagra. We've done this for the conditions of this demonstration and also because you can all see he's wired with a camera so he needs to stay erect for the camera to stay on. Now, young man, will you please position yourself over our young lady, but stay over her - like a planking position - no penetration yet."

"Wait! Some lube!" My sister says excitedly. And she sits up, lifts the bottom of her surgical mask and deepthroats me with a nom-nom slurp and gurgle until she's out of breath. My dick is left twitching and glistening with her saliva. "OK, come here, baby!" she holds her arms open.

The class laughs and the professor chuckles, "Well, that was unexpected! Ok, young man, please assume the planking position!"

I obediently climb over L. and assume the planking. My body is tingling where we are touching which includes my hard dick which is resting on her groin. Our eyes meet over our masks and I quickly look away in case she notices we have the same colored eyes.

The professor walks up to the table and with his gloved hand grabs a hold of my dick, "Class, look at monitor #1 for the penis' point of view. And now at monitor #2 for inside the vagina." Monitor #1 shows an extreme close-up of my sister's labia lips. She is wet and lubed - a dark pink tunnel. Monitor #2 is dark then red, dark then red, as she demonstrates her pussy's clamping power.

"Alright, young man, I will guide you in - notice I've retracted his foreskin - first the glans. Then hold!" I've pushed in my dick head but the professor is asking me to stop and stay in position. "Look at the monitors, class!" It feels so weird to be a couple inches inside my sister. Omigod, I am *in* my sister. Omigod, I'm no longer a virgin! I try to push in a little more.

"Hold this position! Do not move!" The professor commands me.

"You're doing good, baby!" she coos.

"Now young lady, inhale through your nose, draw up your abdomen! Bring in your core. Young man! Hold your planking position!" She begins to inhale deeply and I'm amazed as her pussy walls grip me, like a small hand trying to pull me in deeper by the head of my dick.

"Mmmmmm," she says. "Feels nice." Her hands are feeling my arms and shoulders. She runs her fingers along my back and buttocks.

"Class! Gather around their groin area and watch this puckering motion as she pulls him in. Amazing core strength, young lady! Breathe in through your nose! Hold! Breathe out through your mouth! Again! Breathe in through your nose! Hold! Breathe out through your mouth! Keep that rhythm."

The students take turns looking under me, between us as my dick gets pulled in.

"Feels really good," my sister moans again, "I like the feeling of being spread apart by his erection." She reaches between us and stirs me in a circular motion. It feels incredible - I've got my mouth open, trying not to drool.

"Wow," one student says, "his penis is pulsing!"

"Yes," the professor nods, "His penis glans is wider and broader because I've retracted his foreskin - that helps add to her sensation of being spread. Even the prominent dorsal veining on his penis help provide texture and stimulation. And the vaginal suction? Think of a straw - when you suck on a straw, you draw fluid up. Her core breathing is pulling him into her vaginal canal. And look at the monitors as you see her walls draw him in. How strong is that suction? Everyone take turns holding the base of his penis as you feel her vaginal suction power. Use two fingers like you're taking his pulse."

The class all eagerly giggled as they reached between us for a quick feel of my cock. I couldn't help enjoying the throbbing as my inserted inches were being massaged and stirred by my sister while everyone did a two finger squeeze of the base of my cock. On the monitor, her lips and vaginal walls had the look of the slow progress of a wet, slimy snail wrapping itself around my dick head and shaft.

"You can also feel his scrotum. Evolution has made sure that the scrotum keeps the testes outside the body to lower temperature for maximum sperm production." The professor pulls on my balls. "Good, now please push all the way in."

I oblige, I slide my hard dick all the way in my sister's slick wet pussy. I'm now balls deep, pelvis to pelvis, tummy to tummy, and someone I can't see has their hand between my legs, softly pulling on my sack. The class is half looking at us, and half looking at the monitors where they can see my dick's progress through her ribbed muscled walls. The camera flickers black when she contracts her vaginal muscles and squeezes me in place - I swear it looks so weird on the monitor like my dick is wrapped up with undulating earth worms! My entire body is trembling from keeping this planking position propped up on my elbows. I can't believe how good it feels to be in deep like this. I can't believe my chest is rubbing up against my sister's tits. I want to pull up and start pumping in and out, but the professor's hand is caught in between us, holding my dick like he's holding back an excited dog on a leash.

"I'm going to move my hand out of the way, but I want our young lady to demonstrate a legs up missionary position." The professor steps back, and my sister's legs wrap around my waist. I'm still planking and resisting the urge to pump.

"Class," the professor is at the end of the examination table, "please look here!" He moves my legs apart and reaches to move aside my balls. "Observe how our young man is now in full coitus with the female." I feel his fingers on the base of my dick where I'm buried to the hilt. "And if you look closely, our female is using her vagina walls to continue to grip him. Look at the ring of muscle she has holding him in place. ("Looks like a calamari ring!" one kid says.) This is not only pleasurable for both, but she is also initiating motility so when the male ejaculates, she can move as much semen into her cervical crown as possible. Notice our young man's legs are trembling - in part because I've asked him to hold position and plank - in part, I'm sure because of the pleasurable sensations of coitus. Does anyone know why the female has her legs up like this?"

One kid raised her hand, "To ensure she gets his semen?"

"That's correct. It's pleasurable for maximum penetration - we'll talk about that in the next position - and she is also trying to make he is fully extended so she gets every drop of semen in her cervix when he's ejaculating. All right, young lady, can you move your legs to his shoulders?"

I hold still and take a couple of fast breaths for a couple seconds, as she tucks her legs past my armpits to drape them over my shoulders. I feel like I've sunk in even deeper, savoring the sucking motion of my sister's vagina and the embrace of her soft legs against my neck - this is so much better than a fleshlight. Warmer. Wetter.

"Much deeper extension in this position, isn't it? Thank you, you may pull out."

The entire class awwww'd with disappointment. Even I was disappointed as I sat back, pulling out my wet dick which was red and throbbing. My sister had left a puddle of her juices on the table. The professor took a towel to wipe it off.

"Awwww, class, don't worry, you shall see ejaculation! In this next position, I wanted the best possible view of coitus - both inside and outside. This position is commonly known as reverse cowgirl - it delivers the best views! Now young man, your turn! Please lie on the table."

I happily jump up on the table and lie back with my hands behind my head. My sister gets on top of me, facing my feet, her legs at my side, and before the professor can say anything, she grabs my erection and expertly aims me inside her. I look down to watch my dick slide in and out of her.

"Well, our young lady knows what she's doing!" (the class laughs). "She is in position and riding our young man to have maximum pleasure from his erection at this angle rubbing the clitoral hood. In this position, the woman controls the speed and angle of coitus. Let me grab a hold of his penis to slow things down." The professor grabs my dick and pulls me out. He slaps my dick against my sister's sopping wet pussy, "This is the clitoral hood - she is instinctively getting his penis to rub her there - let's slide him back in." He pushes me back into place while my sister rocks back and forth. I have the strangest sensation as if a giant rolling pin was working its way over my groin.

"Mmmmm," L. whispers, "So good! This is my favorite position. Woman on top."

The class laughs. The professor smiles, "Is it good, young lady?"

"Mmmmm, yes. He's so firm inside me. I love his hard curved dick!" She rubs between her legs, rubbing the underside of my shaft. I can even describe how hard my dick is with all the lathering grinding it's getting from her.

At one point, I pop out and hear the class snicker, but L. murmurs, "That's ok, baby. Let me help" and my cold wet dick is quickly pushed back into her happy, hot cave.

I close my eyes and scrunch my toes with delight as my dick gets worked over by her rocking motions. Someone notices and starts playing pulling at my toes. My sister keeps rocking on me for a while until the professor asks her to stop again. When I open my eyes, I look at her ass and decide that she's gaining weight - she's got a big, dimpled butt.

"Now class, let's watch as our young lady lies back on him so we can get the most explicit and clear view of their genitals together. Now young lady, breathe in through your nose! Hold! Breathe out through your mouth! "

She is doing her pilati-kegel-yoga breathing thing and I can feel my swollen dick pulse in with every breath she takes. The class is murmuring oooohs and ahhhhs of appreciation and amazement. I'm feeling particularly exposed in this position, her head leaned back with her hair in my face, our knees up and legs spread wide showing everyone our penetration in action. I'm proud of myself that I'm not slipping out even though there are outtakes of her breath that makes me think I'll be popping out. I mean I'm just 6 inches, maybe 7.

"Professor!" One student says, "The vagina looks like the mouth of a goldfish!" The class laughs.

"Yes, it does, doesn't it. Her muscles look like a mouth. She has a very well trained vagina! Normally, in human coitus, the male and female would be kissing, using their hands on each other, so remember this doesn't represent reality. I want you all to see the reproductive organs in action. And when you look at the monitor, you can see the female has the most control in this position for her own stimulation. She is using her pelvic motions to maximize the angle of his penis for her pleasure."

"Feels soooo good," my sister moans again. I let out a gasp at a particularly strong downstroke. Then I grab her waist and take a turn at fucking up into her. She moans like a purring cat with every stroke.

At that, he asks L. to get off me with another wet plop as my dick slips out against my stomach. "Final position is commonly known as doggy position. Because of the shape of the average cervix, this is surprisingly not the best position for fertilization but considered to be the most pleasurable for men. The male is in the dominant superior position. He can hold the female down. He controls the angle and speed. There is the added sensation of bouncing against her buttocks. And in the case of a willing female, he can also enter her anally."

There's a cheer from some guy in the back. The professor shoots him a look, "Let's keep this professional!"

My sister gets up on the table on all fours and wags her ass. I climb up and with a nod from the professor, I kneel behind her and easily enter her from behind. I'm thrilled as she moans long and sighs deeply when I'm pushed all the way in. I hold position while the professor points to the monitor and continues his lecture. Meanwhile, I'm rubbing my sister's back and buttocks. I think about giving her a quick slap. This is like my favorite scene in AMERICAN PSYCHO when Patrick Bateman is screwing a hooker from behind. I want to start ramming and cheering myself on in a mirror and on the monitor.

The professor is done talking to the class. He walks over to me, "You may proceed with ejaculation."

"What?"

He looks over at my sister, "Are you ready?" She nods. Back to me, he says, "Do what you need to ejaculate!"