Exaggeration: Larger than life
Incongruity: Unexpected combinations
Recognition: “Isn’t life just like that?”
I don't mean to be egocentric, I'm just drawing from what I know. At any rate, these are the categories that should cause us as human beings to laugh and find something funny. I'll probably be coming back to this post a lot as we go through scenes from Shakespeare to find out why they were funny and why Shakespeare wanted to use comedy.
Cheers!
-Whit