Urinal-Punch
The act of sneaking up behind someone when they are peeing and punching them in the head.
Griffith, having been pushed to his limit, urinal-punched Logan in the bathroom.
Urinal Punch
The act of hitting the guy standing at the urinal next to you while taking a piss with the other hand. Not to be attempted when inebriated beyond a certain point.
Man, I so Urinal Punched Woollard so he pissed over his shoes!