Great Things in Cartoons: Part Five
Innocuous piece of everyday plumbing (eg hosepipe or tap) which is seemingly in perfect working order malfunctions every time it is used by the antagonist. Reasonably assuming a blockage to be the cause of the issue, the character will closely inspect the item at point-blank range. At this point, the item miraculously starts to work again and blasts the character in the face with a powerful jet of water. We laugh as a result of this.