From the rulebook:You and your opponents each move two pawns around the gameboard along the path of colored doors. When you land on a colored door assigned to an opponent, challenge that player to answer a Knock Knock joke. If the challenged player knows the answer to the Knock Knock joke, you are penalized ...your turn is over and your pawn does not advance if the challenged player does not know the answer to the Knock Knock joke, he or she is penalized and must move a pawn backward along the path and you win another spin. As you can see, if you can answer a Knock Knock joke by knowing 'Who's There', you have a good chance of staying in the lead. Be the first player to bring both your pawns home and you'll win the game. - BoardGameGeek