Stumbling into the bathroom, I find my friend already there, cock in hand, lost in his private pleasure. His eyes widen in shock, but he doesn't stop. I'm frozen, watching his tight grip, the pre-cum beading at the tip. He's embarrassed, but there's a thrill in his eyes, a challenge. I back out slowly, leaving him to finish, but the image of his flushed face and hard cock lingers.