The social function of laughter

Researchers find that laughter often has a social function that can be relatively unrelated to actual humor.

One thing that is probably helpful to keep in mind, though, is that what is humorous is highly dependent on context - the attempt to find, beyond broad archetypes, something "objectively funny" is a wild goose chase.  Everyone knows that jokes from other cultures can be hard to understand, but even among people you know well, how many times have you found yourself trying to explain something funny after the fact and giving up and saying "You just had to be there"?