They play a game of 8-ball (what most of us just call "pool")) with some m*** rules variations.
No immediate loss for scratching the 8-ball, mainly... I didn't want the game to suddenly come to an end before someone was naked. Sink one of your opponent's balls, and she loses a piece of clothing. Sink all of your opponent's balls, and she's naked. Sink all of your opponent's balls and the 8-ball, and she's naked and doing whatever you tell her to do. In front of the audience.