Buy cheap latex/surgical gloves (you can find them at supermarkets or at paint supply aisles in hardware stores). Two to three kids up front put the glove on their head, pulling it down to just between their nose and mouth. Each kid races to blow the glove up by breathing in through their mouth and exhaling out their nose. It helps to have them hold the glove on their face with their hands. Generally, the more hair, the less successful, but I have seen guys blow the thing up 2-3 feet above their heads! This is a great opportunity to take pictures.