Odds and evens, also known as choosies, pick, odds-on poke, or bucking up, is a hand game played between two people,[1] used to decide an issue. This game, a variation of the ancient Morra, is played internationally, especially among children.
The individuals prepare by deciding who will be assigned odds and who will be evens. Then, one or both people say "One, two, three, shoot!". As the word "shoot" is said, the two people quickly and simultaneously thrust a fist into the center, extending either an index finger, or both the middle and index finger, indicating one or two. The sum total of fingers displayed is either odd or even. If the result is odd, then the person who called odds, is the victor, and can decide the issue as he or she sees fit.[2][3][4] Often, the participants continue to shoot for a best two out of three.[5]
In a single game, the chance of either person winning is 50%. [6] This is significantly more random than playing consecutive games of rock, paper, scissors. Since any single player can change the result to any other player, a nonrandom result requires the simultaneous cooperation of all players. While unwitting cooperation based on manipulating human psychology can be achieved with successive games of rock, paper, scissors by skilled players, the difficulty of simultaneously predicting the throws of all other players in a single expanded game of odds and evens is much greater.