She asks for advice.

Sophia looks torn. She's obviously getting turned on...her cheeks are flush, her exposed nipple looks hard as a rock underneath her fingertips. But at the same time, she's kind of out of her depth. This is obviously new territory for her. You're as sympathetic as you can be considering how turned on you are.

She pauses for a moment, covering her breast with her palm, perhaps out of modesty since she's talking to her teacher now. For some reason you find that even sexier, although you also slow down your own stroking.

"Well," Sophia says haltingly, "I mean, this is sex-ed right? So, I should be learning something?"

"That's right," says Diana, "You just got to learn how turned on a man can get when he sees a woman undressing, and you also got to see how a man can pleasure himself. But the next part of the class was going to be an anatomy lesson and then I was going to give the class a chance to learn how to pleasure a man."

You can see Sophia's breath speed up when Diana says "pleasure a man". Her eyes dart again to your cock, still only a foot or so from her face.

"Well," Sophia repeats, "What else can I learn here? What would you do if you were me?"

Diana, still obviously frustrated, responds bracingly, "what do you mean?"

"I mean, if you were sitting here, half-undressed, and there was this sexy guy, with his penis hard, standing right in front of you," she looks transfixed at your cock, her fingers starting to play with her nipple again. You notice she's loosened her hold on her shirt, and it is slowly sliding down her body, exposing her other perfect breast. Aside from her panties and the shirt hanging down from her lower back, she's all but naked in front of you. You start stroking yourself harder. She continues, almost whispering "if all that was happening to you? What would you do?"

Diana smirked. "Well, I shouldn't really answer, since sharing my own preferences isn't the most professional thing in the world, but, I'd probably grab his dick and start sucking it."

You looked up at her, startled to hear your friend saying something like that about you, when out of the corner of your eye you see a motion, and you feel something soft and wet surround the head of your cock. A shock of warm pleasure washes through you.

You look down to see the top of Sophia's head as she sucks hard on your cock. You can feel her tongue pressed against the front, just where the head meets the shaft. It works up and down as if she was sucking on a lollipop.

Overwhelmed by how amazing her mouth feels around you, you push deeper in. She takes you a couple more inches, then grabs your shaft with both hands to stabilize as she begins taking you in and out of her mouth rapidly, sucking hard on your glans every time she pulls away.

You completely lose it.

In a wave of primal ecstasy you release yourself into mouth, pumping blast after blast into her, holding onto her head with one hand and her bare shoulder with the other hand, just trying to keep your balance. You think she's going to pull away, but she doesn't stop, she just keeps sucking, slowly softening her pressure as you finish orgasming.

When you're done, you look up, dazed. The class is staring at you wide-eyed, no idea what to think Diana looks aghast, obviously completely shocked by what happened.

You look down at Sophia, who has finally come up for air. She has a tiny white smear on the side of her lip, and two erect nipples, and the sweetest smile you've ever seen as she looks you straight in the eyes.

Totally worth it.