Rock-paper-scissors-lizard-Spock is a five-gesture expansion of the classic selection method game rock-paper-scissors. It operates on the same basic principle, but includes two additional weapons: the lizard (formed by the hand as a sock-puppet-like mouth) and Spock (formed by the Star Trek Vulcan salute). This reduces the chances of a round ending in a tie. The game was invented by Sam Kass with Karen Bryla, as "Rock Paper Scissors Spock Lizard".
The game was mentioned in four episodes of The Big Bang Theory. According to an interview with Kass, the series producers did not ask for permission to use the game, but he was later referenced in an episode in the fifth season. It has been used to understand the transitivity of climate change policy choice.
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