The traditional game of Rock, Paper, Scissors needed more possibilities, because the odds of the game ending in a tie were too great. So Sam Kass¹ added two more variables – a lizard, and Spock from Star Trek. The game has been in three episodes of The Big Bang Theory, and it truly is best to have Sheldon explain how it is played:

Here’s a handy reference guide I saw on Google+² to help you play next time there’s a score to settle: