Peter McGraw, professor of psychology and marketing at the University of Colorado Boulder, has figured out what makes you laugh…and what doesn’t. His work has yielded a kind of grand unifying theory for all things humorous. It’s called the Benign Violation Theory.

Basically, McGraw says that we laugh when we perceive a violation has taken place that is truly harmless.

A dad on some Youtube videos gets whacked in the man parts by a toddler’s well-aimed baseball? Violation of personal dignity. But I don’t know him personally and, well, he’ll walking it off so…funny.

Pedophilia? Ample violation of norms. But not benign in the least. Not funny.

When a norm is violated in a way that is harmless we laugh. That’s the extent of McGraw’s theory. But why not take it a step further?

So when you laugh you’re telling me a lot more than you may have realized. When you laugh I get a sense of what your norms are and what you consider harmless. And when you don’t…

When you laugh at yourself? Awesomely secure, confident individual.

When, just after that, your date asked if you’d still think she was pretty if she had only one arm? That look on your face? Hilarious.