Rock Paper Scissors is a popular game which uses 'weapons' in a battle to decide a winner. This is often used to settle disputes, however it has been proven that if you and your opponent know each other well, you will tie 75 - 80% of the time.
"One popular five-weapon expansion, invented by Sam Kass, adds "Spock" and "lizard" to the standard three. "Spock" is signified with the Star Trek Vulcan salute, while "lizard" is shown by forming the hand into a sock-puppet-like mouth. Spock smashes scissors and vaporizes rock; he is poisoned by lizard and disproved by paper. Lizard poisons Spock and eats paper; it is crushed by rock and decapitated by scissors. This variant was mentioned in a 2005 article of The Times, and appeared in an episode of the sitcom The Big Bang Theory, "The Lizard-Spock Expansion," in 2008." - Wikipedia