Sure you can always play the pizza roulette John posted, wherein one unlucky eater gets a slice of pie coated in pepper juice, but for those of you who aren't total jerks, the pizza plate roulette is a lot more friendly. In this game, the person who gets the slice on top of the black dot has to pay for the whole meal. Of course, that also means you'd better slice the pie correctly or else the pieces won't line up right and then there will be a fight over whose slice covers more of the black dot...and no one wants to deal with that nonsense.
Link Via Laughing Squid