Piss Disc
A prank, prevalent in college dorm rooms, in which the prankster urinates into a disc (such as a plate or frisbee) and freezes it in his/her refrigerator. After the urine is frozen, the perpetrator carefully removes the frozen disc from the container and slides it underneath a victims door. The piss subsequently melts and leaves a gargantuan mess.
"Dude, I heard Joey egged your car last night!"
"It's okay, I'm going to hit him with a piss disc later."
"It's okay, I'm going to hit him with a piss disc later."