HISTORY OF RUSSIAN ROULETTE
Russian roulette is a potentially 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 being reminiscent of spinning a roulette wheel.
Because only one chamber is loaded, the player has a one in n chance of hitting the loaded chamber, where n is the number of chambers in the cylinder. So, for instance, for a revolver that 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.