Interesting thread. I've actually done a fair amount of research on "Theory of Humor" and you know what? NOBODY KNOWS why we laugh at things. There
are many theories, but nobody has been able to pin anything down.
The best theory of humor I've ever found is here:
www.tomveatch.com...
This paper presents a theory of humor, that certain psychological state which tends to produce laughter. The theory states that humor is fully
characterized by three conditions, each of which, separately, is necessary for humor to occur, and all of which, jointly, are sufficient for humor to
occur. The conditions of this theory describe a subjective state of apparent emotional absurdity, where the perceived situation is seen as normal, and
where, simultaneously, some affective commitment of the perceiver to the way something in the situation ought to be is violated

Tom Veatch is a Professor of Linguistics at Standford. The above link, in addition to being very informative, is also quite humorous in places.
However, I think he falls short in his theory. For example, he struggles with why some people find "puns" funny.
This would be a good link for ATS, but it would probably be wasted there. I think it best belongs here in BTS.
Edit: You know what is odd? There is actually an official "International Journal of Humor Research", where this paper was first published in 1998.
I guess a lot of people are working on this subject. I did a web search, but I don't think this Journal is available online.
None of this is funny. But I think it is interesting.
[edit on 24-7-2008 by Buck Division]