Russian Roulette

Russian roulette (Russian: Русская рулетка) is a lethal game of chance in which a player places a single round in a revolver, spins the cylinder, places the muzzle against their head, and pulls the trigger. "Russian" refers to the supposed country of origin, and roulette to the element of risk-taking and the spinning of the revolver's cylinder, which is reminiscent of a spinning roulette wheel.

Because only one chamber is loaded, the player has a one in x chance of being shot; x is the number of chambers in the cylinder. So, for instance, if a revolver holds six rounds, the chance is one in six. That assumes that each chamber is equally likely to come to rest in the "correct" position. However, due to gravity, in a properly maintained weapon with a single round inside the cylinder, the full chamber, which weighs more than the empty chambers, will usually end up near the bottom of the cylinder when its axis is not vertical, altering the odds in favor of the player. This only applies to swing-out cylinder type revolvers, and only if the cylinder is spun outside of the revolver and allowed to come to a complete stop before locked back in. The number of pulls of the trigger before a round is expected to discharge is 3.5 (without spinning between the pulls) or 6 (with spinning between the pulls).

In Mikhail Lermontov's "The Fatalist" (1840), one of five novellas comprising his A Hero of Our Time, a minor character places a gun with an unknown number of bullets to his head, pulls the trigger and survives. However, the term "Russian roulette" does not appear in the story.

The term "Russian roulette" was possibly first used in an eponymous 1937 short story by Georges Surdez. However, the story describes using a gun with one empty chamber out of six, instead of five empty chambers out of six:

There is a drinking game based on Russian roulette. The game involves six shot glasses filled by a non-player. Five are filled with water, the sixth with vodka. Among some groups, low quality vodka is preferred as it makes the glass representing the filled chamber less desirable. The glasses are arranged in a circle, and players take turns choosing a glass to take a shot from at random.

...
Wikipedia