The Antigravity Apple is the head of the Department of Improbable AUs. It used to be the head of the Physics Division of the Legal Department. Where it came from is unknown, but it sounds like something that would happen on the Discworld. Whatever its origin, it is probably a cosmic relative of the apple that is famously purported to have hit Isaac Newton on the head, inspiring him to develop the theory of gravity. Every family has a bad apple...