A bewildering card game invented on the spot by James T. Kirk to distract his gangster captors on Sigma Iotia II, with rules that change by day and hour.
Fizzbin has no real rules. Kirk makes it up in the episode A Piece of the Action while he, Spock and McCoy are held at gunpoint by the men of Bela Oxmyx on Sigma Iotia II, a world that has modelled itself on the Chicago gangs of the 1920s.
Sitting down with the guards' cards, Kirk explains that each player gets six cards except the man on the dealer's right, who gets seven, that two jacks make a half-fizzbin, and that a third jack is a disqualifying shralk. The requirements change at night and on Tuesdays.
When he lets a card drop and a guard bends to pick it up, Kirk overturns the table and the three overpower their captors. Quark later mentions the game in Deep Space Nine.