Set up several balloons with strips of paper inside which say to do silly things (sing "New York, New York, bark like a dog, do the Charleston etc.) Place all the players in a circle. Pass a balloon around the circle. Each player has to sit on the balloon with all their weight for 3 seconds. If someone breaks the balloon, they must do what it says on the message.
Here are some crazy ideas:
1. Read from the phone book as a Shakespearean actor.
2. Act out this scene - a cow being branded
3. Do and sing the macarena
4. Sing jailhouse rock as Elvis