Exposing a single testicle through the opening in the zipper in a exhibitionistic manner, usually to another cooperating party. This can become a game where you see who can show their naked brain in the best location (supermarket, restaurant, library), where the most outrageous location wins the game.
Steve and I went down to the Piggly Wiggly on friday night and I managed to sneak a naked brain out near the frozen foods. He then retaliated and got me back over in the produce section.
by Eric Crouch December 29, 2004
Get the Naked Brainmug.