A card game described by James T. Kirk to the natives of Sigma Iotia II during the Star Trek 'original series' episode A Piece of the Action.
According to Kirk, Fizzbin was a card game popular on Beta Antares IV. To start a hand of the game, players get 6 cards, except that the player on the dealer's right gets 7. The second card is turned up, except at night. Two jacks make a half fizzbin, but 3 jacks are a shronk which loses immediately. With 2 jacks you need either a King and a deuce, except at night when you need a Queen and a four. You get another card if you draw a king, unless it's dark, in which case you give it back. Goal: the elusive Royal Fizzbin.
Of course, Kirk was making it up on the fly. He'd used it as a way to distract some guards who were holding him, Spock, and McCoy prisoner. The guards had been playing poker. Kirk gets them interested by telling them fizzbin is a "real man's game" and when they are suitable engrossed in the complex rules, our heroes overcome them and escape.