John von Neumann is a key figure in game theory, mathematical economics, and linear programming (among many other fields) — a wearer of many hats. According to collaborator and economist Oskar Morgenstern, von Neumann also enjoyed wearing funny hats.
Whenever Johnny saw a funny hat, he’d put [it] on…He had one with a little contraption that made a noise when you blew into it, and a light would flash at the same time. It was one of those children’s things, and he loved it.
More found in John von Neumann, a Documentary(1966), from the Mathematical Association of America.