Imagine you're jumping on a trampoline, you're wearing basketball shorts and a t shirt, no underwear, so loose you can feel the air all in your shorts and on your dick when you jump. You just feel naked.
You see her jumping like this, sticking her ass out, just taunting you with those gigantic cheeks. You see their every jiggle, you watch it for a full minute, dick rock hard.
Everyone who glances can see it, and you can feel it rubbing against the fabric of your shorts. Everyone's already seen your erect cock, you could care less now. You fucking lunge at her and your fully erect cock, still in shorts, slams against her right cheek in the middle of her jumping. You press up against here and your dick pops directly in between her cheeks. You hug her as tight as possible and jackhammer your dick between her cheeks, fabric rubbing against her and your dick, pelvis slapping against her ass. You cum and release three gigantic spurts of super this jizz, there's so much that it's shooting out of the legs of your shorts. You've fully came and your head slams against the floor and you're out cold.