Her Ass

You approach her from behind as you unzip your pants and pull your dick out. "Spread your cheeks" You tell Supergirl and she does.
"You're not going to go in my no-no place are you? No ones ever- oh!" You answer her question by sliding your dick into her tight anus. This seems to shut her up for a while. She uses a combination of Super-strength and flight to keep her body at a 90 degree angle as you fuck her hard in the ass. You reach forward and slide up her shirt, to allow you to feel her small but firm breasts. She can obviously take a pounding, she is Kryptonian after all.
Soon you feel yourself ready to blow.