Get very friendly

"If you want to be a good friend," you tell Stacy, undoing your jeans and pulling them down deftly, "come over here and sit on my cock."

Stacy bites her lip and furrows her brow with anxiety, but gets up and moves around to your desk.

"Is something the matter?" says Mrs. Susan.

"Stacy's desk chair seems unstable, she's just moving to mine," you say, offering no explanation as to why Stacy's blouse is open or why she wouldn't simply move to a different desk.

"Fine, carry on," says the teacher.

Stacy walks over to your chair and tentatively straddles you, not seeming entirely sure of what she's doing. "John, I want to fuck you so bad, but I don't know what you have in mind here."

You grab a handful of her tit-flesh, and gently guide her down so that her pussy lips are spread by your cock. "I want you to ride my cock a bit to get it nice and lubed up," you tell her. You pull her down more and slide forward, entering her easily despite your girth.

"AAAH," she says. The class momentarily goes silent, and you can sense the classmates turning to look. Stacy can apparently sense it too, because she starts hyperventilating. After a moment, the class carries on.

"John, everyone's seen me sitting on your cock," she whimpered.

"Sssh," you say, releasing her breast and embracing her. "You're being a good friend." You hold her while her pussy gently clenches on your member, trying to accommodate it. After half a minute you prop her up and give her another kiss, focusing on her lips at first, and then delving inside once more.

When you come up for air, Stacy still looks anxious, but more at ease and happier. "You're such a good friend, John. And I love having your cock inside me. I just hope that this doesn't come between us," she says.