A Urinal Kick is an epic maneuver in which some guy is taking leak in a urinal in a bathroom and you kick the back of his knee, causing him to fall backwards onto the disguisting piss-covered floor, possibly pissing into the air onto himself. Not cool unless you really hate the person. Seriously.
I U.K'ed (Urinal Kicked) that asshole who cut me off on the way to work. He deserved it. Seriously.