as 1/n, so the probability of a tie is 1/3 in standard rock paper scissors, but 1/5 in a version that offered five moves instead of three. One popular five-weapon expansion is "", invented by Sam Kass and Karen Bryla, which adds "Spock" and "lizard" to the standard three choices. "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 in The Times of London and was later the subject of an episode of the American sitcom The Big Bang Theory in 2008 (as rock-paper-scissors-lizard-Spock). A game-theoretic analysis showed that 4 variants of 582 possible variations using 5 different weapons have non-trivial mixed strategy equilibria. The most representative game of these 4 is "rock, paper, scissors, fire, water". Rock beats scissors, paper beats rock, scissors beats paper, fire beats everything except water, and water is beaten by everything except it beats fire. The perfect game-theoretic strategy is to use rock, paper, and scissors of the time and of the time for fire and water. Nevertheless, experiments show that people underuse water and overuse rock, paper, and scissors in this game. Analogues in real life Lizard mating strategies The common side-blotched lizard (Uta stansburiana) exhibits a rock paper scissors pattern in its mating strategies. Of its three throat color types of males, "orange beats blue, blue beats yellow, and yellow beats orange" in competition for females, which is similar to the rules of rock-paper-scissors. Bacteria Some bacteria also exhibit a rock paper scissors dynamic when they engage in antibiotic production. The theory for this finding was demonstrated by computer simulation and in the laboratory by Benjamin Kerr, working at Stanford University with Brendan Bohannan. Additional in vitro results demonstrate rock paper scissors dynamics in additional species of bacteria. Biologist Benjamin C. Kirkup Jr. demonstrated that these antibiotics, bacteriocins, were active as Escherichia coli compete with each other in the intestines of mice, and that the rock paper scissors dynamics allowed for the continued competition among strains: antibiotic-producers defeat antibiotic-sensitives; antibiotic-resisters multiply and withstand and out-compete the antibiotic-producers, letting antibiotic-sensitives multiply and out-compete others; until antibiotic-producers multiply again. Rock paper scissors is the