The theory that all male-identifying individuals can be categorized as either a pirate, a cowboy, or an astronaut. Some combination thereof is a possibility, but one classification is always dominant. The categories need no defined criteria because the correct placement is almost always surprisingly obvious.
"I really like him, which is surprising because based on The Pirate Cowboy Astronaut Theorem he's more of an astronaut, and I'm usually more attracted to pirate men."
"I get that. I'm mostly into cowboys at the moment, but I could definitely see myself settling down with an astronaut one day."