Ask families to bake cakes and donate them to the PTA carnival. (Local bakeries may donate cakes, too.) A cake walk is similar to the game musical chairs. People can buy a cake walk ticket to participate and receive a number. They stand in a circle, then music is played. When the music stops, a number is drawn, and the person with that corresponding number gets to choose a cake to take home.
Many students would love the opportunity to throw a pie in the face of a favorite teacher or administrator. Sell tickets to participants. Get a few teachers and the principal to participate. Then, ticket holders have one chance to throw a pie in the person's face.
If the PTA carnival is held in the school's gym, have a basketball hoop-shooting contest. Participants can pay, for example, $5 to make 10 free throws. And the person who makes the most free throws can win a prize (donated by an area business).