Diana interrupts for a quick anatomy lesson.

"OK!" Diana says a little louder than necessary, stepping in to separate you from Samantha before things get out of ha-- well, before they continue being in hand I suppose. Your hands is very sad to lose her breast. "Good job getting Joe erect, Samantha. Maybe a little too good, but I won't complain. Let's continue with the class plan for the day, shall we?"

With a grin Samantha steps back, nodding at her teacher. She grabs her top back from the floor and slips it on, but leaves her skirt and bra on the floor. She buttons her blouse back up as she sits down, staring right at you.

"I'd like to show you all some of the basic features of Joe's penis." Diana says, trying to compose herself after the very heated moment that just passed.

You're still extremely turned on, and seeing Samantha cross her beautiful, very revealed legs isn't helping. Meanwhile, Diana, fully dressed but equally beautiful in her slightly nervous but heroic effort towards professionalism, is standing quite close to you.

She continues, "Joe, is it okay if I touch you while I talk? Class, Joe and I are actually friends outside of class, so this is a little unusual as far as situations go. Joe, it's totally ok for you to say no, I'd understand. But in past classes I often touch the models to demonstrate before letting the girls do it."

Your intensely hot friend is asking you if she can touch your dick in front of a bunch of pretty girls. Um, yes please. You play it cool. "Yeah, totally, whatever you need to do."

"Thanks Joe. So, class, this is the shaft of his penis." She stands next to you, and reaches down, wrapping her hand around your hard cock, holding it in a loose grip. You have to use your will power not to thrust into her hand. "Thanks to Samantha, he's already nice and hard. Can anyone tell me why his penis is hard?"

The blonde in the front row instantly raises her hand.

"Grace?" Diana calls, her hand still wrapped around you. You can smell her shampoo from this distance, she's only inches away.

"It's hard so he can penetrate a woman's vagina," Grace says.

"Correct," Diana says, "So, if he's inside a women's vagina, and he stays hard by moving in and out, then what would I do right now if I wanted to keep him hard?"

Grace's hand shoots up again, breast bouncing lightly with the movement.

"Someone besides Grace?" Diana asks.

Samantha, lounging back in her chair, raises her hand. Braless, you can see the slight outline of her breasts and nipple under her blouse. You unconsciously push slightly into your friend's hand, and she holds steady, allowing you the pleasure of the slow thrust.

"Samantha," Diana calls, "What would I do with my hand?"

"Pump it," Samantha says, "Simulate a vagina by gripping his penis and then sliding your hand up and down."

"Let's try it and see what happens," Diana says playfully. She increases her grip on your cock and starts slowly sliding it up and down. You gasp and this time you do push yourself into her hand. You look down and see the head of your cock appearing and disappearing and she slowly pumps you. She looks up at you, blushing the slightest bit, and speaks under her breath to you, "Are you sure this is ok, Joe?" You nod assertively.

After a few timeless moments, she lightens her grip and slows her pumping. "It looks like you were right, Samantha. He's extremely hard right now."