Similar to RockPaperScissors, except more painful.
Each player kicks the opponent as hard as possible in the genital region. The first person to fall down is the loser.
Player 1: "Hey, I'll rowshambo/rochambeau you for the first slice of pizza!" XD XD
Player 2: "OKAY~!!" ^_^ ^_^
Player 1: "Me first!" *evil grin*
*swift kick to groin of Player 2 by Player 1*
*Player 2 falls over in immense pain, Player 1 laughs and eats pizza.*