Russian roulette

(a) act of bravado in which a person holds to his head a revolver of which one (unknown) chamber contains a bullet, and pulls the trigger 俄罗斯轮盘赌（逞能冒险举动, 用只装一发子弹 的左轮手枪对准自己头部扣动扳机）: play (at) Russian roulette 玩俄罗斯轮盘赌. (b) (fig 比喻) any action or situation involving serious and unpredictable risks 严重而不可预测的冒险行动或情况.

runway, rupee, rupture, rural, rural dean, rural delivery, Ruritanian, ruse, rush, rush hour, rush into, rush out, rush sb. to..., rush through, rush-hour, rushy, rusk, russet, Russia, Russian, Russo-, rust, rust-proof, rustic, rustically, rusticate, rustication, rusticity, rustily, rustiness, rustle, rustler, rustling, rusty, rut, rutabaga, ruthless, ruthlessly, ruthlessness, rye,