'Russian roulette' definitions:

Definition of 'Russian roulette'

noun

A stunt in which you spin the cylinder of a revolver that is loaded with only one bullet and then point the muzzle at your head and pull the trigger

From: GCIDE

Russian roulette \Rus"sian roulette\ (a) An act of bravado played by loading one bullet into one chamber of a revolver in which the cylinder has five or six positions, spinning the cylinder (thus moving the bullet randomly to one of the six positions of the cylinder), pointing the gun to one's head, and pulling the trigger. If the bullet is in firing position, the "player" is usually killed. Such a "game" may be played on a dare, or, in some places, as part of a gamble. (b) (Fig.) Any dangerous act resembling Russian roulette in the acceptance of a high risk of serious negative consequences, usually unnecessarily. "The congress is playing Russian roulette with the economy by enacting such large tax reductions without spending cuts." [PJC]