The Makey Makey is a small, cheap and relatively easy way to turn almost anything into a control pad. Acting as the underlying board, the Makey Makey lets you attach alligator clips to objects which then transform them into d-pads and buttons.
So...anything conductive you can get your hands on, whether it be food or whatever, can now be made into a very messy, albit delicious, controller.
It'll also work as a regular computer input, but come on. With a D-pad and two buttons it's fairly obvious it was designed so you can play Super Mario Bros. with a sliced banana.
Makey Makey, A Kit for Connecting Everyday Objects to a Computer [Laughing Squid]