We laugh when we’re happy and we cry when we’re sad, but sometimes it’s not always black and white. Shows like America’s Funniest Home Videos and Impractical Jokers provide us with slapstick humor that elicits laughter at the expense of others. Although everyone has a different sense of humor, why is it universal to laugh when someone falls down or gets hit in the groin?

Play Frame

Dr. William F. Fry, psychiatrist and founder of gelotology — the science of laughter — at Stanford University suggests, “play frame” puts a real-life event in a non-serious context that prompts an unusual psychological reaction. In other words, this explains why, while it's not humorous seeing someone fall to his death from a six-story building, it can be funny to see someone fall on the street. A serious overtone is set when someone falls out of a window and dies, whereas someone who trips and falls on the street is just embarrassed.

Incongruity

Laughing because someone unexpectedly falls over is linked to incongruity. This term is used to describe why we laugh at things that convey ambiguity, logical impossibility and inappropriateness. For example, it’s comical when we see clowns wear large shoes or when people have especially large noses.

Maintaining Rules of Society

Philosopher Henri Bergson theorized society trains people to laugh at careless and eccentric behavior as a means to set guidelines for society. In the instance when people fall, chances are they were not attuned to their surroundings or were acting ridiculously. Laughter acts as a reminder for those around us to pay attention to the rules of a society, because no one likes to be laughed at, and laughter pushes us to “being normal.”

Asserting Superiority

Bergson’s theory can also coincide with philosopher Thomas Hobbes’ theory — laughter arises from a feeling of superiority. In Hobbes’ Leviathan he argues the burst of laughter directly following someone’s misfortune is an extension of feeling a “sudden glory.” Laughing at someone’s pain or public ridicule could be a way of belittling others, or for others in a lower hierarchal status to gain power. For example, Zach Morris, a student on Saved By The Bell always tries to one-up Principal Belding with his schemes.

Mirror Neurons In The Brain

Reacting with laughter when we see someone fall down might just naturally be in our brains. Some neurologists suggest the presence of mirror neurons — neurons that fire inside an observer’s brain that mirror those of someone else performing an action — could make us feel as if we are the ones that are falling or acting silly. Our brains recreate the brain activity of the person who’s actually falling and provoke us to laugh.

Mental Distance

The more psychological distance from publically humiliating situations we have, the more likely we are to laugh out loud. In a 2010 study, psychologist Peter McGraw at the University of Colorado explains seeing others getting hurt is funny when the viewer doesn’t feel empathy for the victim. The guys on shows like Jackass always get hurt, yet this is highly comedic because we distance ourselves from them and don’t empathize with their shenanigans. Meanwhile, if we know the victim, these misfortunes aren't at all funny. Here, closeness increases feelings of threat and insecurity because we simply become too close for comfort.

These theories provide an explanation to why we find public humiliation like tripping or getting kicked in the groin comedic — at least until it happens to us.