I´ve always thought that people who are really funny are that way because they have had a rough life. People laugh to come to terms with whatever they are having a hard time with. The reason I thought about this was a joke that I have with a friend of mine. She works with the street kids, abut five or so years old. I work with boys aged 12 to 18 who are in jail, and the joke is that in a few years I will be teaching her kids English...which isn´t very tactful, but also the other day the kids at the jail had a talent show and a group decided to perform a play that they had written themselves.
In short it was about a kid who was playing soccer and having a fun day untill his drunk father needed cash for more alcohol. The kid went out begging for money and finially met up again with his father who wasn´t happy with the small amount of money his son had brought home. So the Dad beat the son to death. The audience loved it. They thought it was the funniest thing they had ever seen.