I’m a firm believer in the old saying that if you have to explain a joke, the joke isn’t funny anymore. Even E.B White once said that "analyzing humor is like dissecting a frog. Few people are interested and the frog dies in the end."
The risk of frog-killing notwithstanding, a growing number of academics have dedicated their research to pinpointing exactly what makes something funny? Their theories are, well, quite serious. Some assert that humor is psychologically driven by the people around us. Charles Darwin himself suggested that humor is a crucial social cohesive, one of the primal forces that has bound tribes together throughout evolution
Another explanation for finding things funny comes in the form of the incongruity theory, the idea that we laugh when we're surprised. Other reasons for humor include the so-called "superiority theory," which claims that we laugh in the face of other people's misfortune as well as the relief theory, which asserts that "funny' is derived from fear. One study deliberately startled test subjects with a convincing fake rat, eliciting a lot of relieved laughter.
Finally, a recent idea called the "benign violation theory" hypothesizes that we laugh when we're harmlessly violated. This could mean anything from tickling -- which most people hate but still laugh at -- to vulgar stereotype-based humor.
Ultimately, we may not know the exact reason for what makes something funny, but one thing we do know is that it's innate. After all, people born deaf and blind are able to laugh without having ever seen or heard it done. So whatever our internal motivation to laugh, it's probably best not to over-think it -- just sit back, grin and enjoy it.