Bart's Weather Balloon, also known as the "Hi! I'm Big Butt Skinner!" Weather Balloon and the "Buttzilla" Weather Balloon, was a school-owned weather balloon created for the school's Science Week that was sabotaged by Bart Simpson by placing folds that unfold at the pull of a string upon launch to give the illusion of Principal Skinner bending down and having an enormous butt sticking out of his pants, with him holding a sign. Bart attempted to hasten the launch of the balloon on the final day of Science Week by cheering loudly for Science. As soon as it lifted off, however, Bart pulled the string to reveal the modifications he made to the balloon, to the children's amusement and to Skinner's horror. He attempted to get it down itself, and then had the children throw rocks at it (promising