It's very simple. Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, and, as it always has, rock crushes scissors
Sheldon: Why do you have the Chinese character for "soup" tattooed on your right buttock? Penny: It's not "soup," it's "courage." Sheldon: No it isn't. But I suppose it does take courage to demonstrate that kind of commitment to soup. Penny: How'd you see it? You said you wouldn't look. Sheldon: Sorry. As I told you, the hero always peeks.