Rock, Paper, Scissors, Lizard, Spock T-Shirt

Rock-paper-scissors-lizard-Spock is an 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[1] (formed by the Star Trek Vulcan salute). This reduces the chances of a round ending in a tie (from 1/3 to 1/5). The game was invented by Sam Kass with Karen Bryla, as "Rock Paper Scissors Spock Lizard".[2][non-primary source needed]

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 the episode "The Rothman Disintegration" from the fifth season, for which he thanked them on his website.[3][self-published source?][2]