The moderator provides a relationship between two people or an activity. Two players begin to act out the scene. The scene can be stopped at any point, and one of the players can be replaced by another actor. This new actor is the is the evil twin of the person whom he has just replaced. This twin does something evil, horrible, or bizarre and then changes places again with the original actor. Now the original actor must justify his strange behavior.
by Guido Boyke