You reach down to Cory's presented posterior, and poke it with your index finger. Cory lets out a sensual moan and says "just grab it numbnuts" as they shove their butt closer into your palm.
It feels really soft and smooth, so you put your other hand on the other cheek and start to rub. "oooh yeah like that dude" Cory lets out, and continues to back into you. Trying to keep some personal space, you soon find yourself backed up into the wall; and Cory shoves their butt square onto your pelvis. Your dick confined inside your underpants and gym shorts takes the shape of a wrapped-up hot-dog, while Cory articulately flexes their buns around it.
Your heart is pounding, you've never felt anything like this before; you soon find yourself reaching down to pull your dick out of it's confined space within your shorts. Cory's butthole is right there, and all you can think of is to shove your throbbing member into it. Cory lets out a bigger moan as it slides in, then begins to pull it out, push it back in, twist, twerk, any motion you can think of.
Suddenly you feel yourself reaching climax, "dude im gonna cum", but instead of getting off your dick, Cory pushes down and clenches their hole around you, and you release your load inside of Cory's butt. You slump down the wall onto the ground in a daze. a simple "woah" is all you can manage to let out.