In tiny briefs, the yaks and ox cavorted in their daks and jocks, when from outside arose a din. "Stop!" squealed Pig. "You can't come in!" When Elephant, Snake, Hen and Spider turn up to the Ball without any undies on, they are not allowed in. But each of them has a very good reason why, and in the end Lion decrees that for future events they should all wear their Birthday Suits!