One of five-minute craft projects for kids— a balloon face. The idea isn't new, I saw similar projects on many sites on the Web, you can even buy a craft kit for it.
Inflate a balloon and draw a funny face on it using permanent markers. Cut out cardboard feet and decorate them. Attach the balloon to the cardboard using an adhesive tape. The feet should be big enough to hold the balloon steadily. Have you balloon wear a funny hat: a ribbon, a paper top hat, or a cap. Ours was wearing a doll's hood, but the doll asked it back right before the picture was taken :)