Samurai is a physical concentration warmup.
All players stand in a circle. One player makes a throwing noise and throws an imaginary knife at another player, who mimes getting hit with the knife and makes an "erk" noise. The two people on either side of the person who has been stabbed then mime slicing the person who was stabbed with samurai swords while making a "hai-ya!" sound. The person who was stabbed then throws a knife at someone else, and play continues.
Samurai comes down to the verbal rhythm of throw ("ya"), getting stabbed ("ugh"), and slicing ("hai-ya!").