Act pissed about it

Jonathan waited until Brian's gaze fell over his bulge, and all of a sudden said:

"HEY, wtf dude?!"

Brian got spooked a little and looked scared

"Huh? What do you mean, ma..."

"You were staring at my crotch, what the hell, man?"

"Sorry, I didn't mean to ..."

Jonathan gets to the other end of the locker room, leaving Brian alone.