After reading Osip’s fateful SBD flatulence thread, and laughing with it, as everyone else has, the following thought occurred to me:
Why is farting humorous?
I laugh at it. Most everyone else laughs at it but WHY? Hmmm
Maybe it depends on the circumstances surrounding the event, I don’t know.
Um… yeah.
Farting in and of itself is not humorous.
Farting in an inappropriate place is, therefore farting has and essence, if you will, of taboo. Any taboo is humorous.
Especially among eight year olds and, apparently, Dopers.
Well I laugh, when I, err, cut the cheese, even by myself. I think it’s more out of being pleased with myself than anything else.
I tend to laugh when it’s a silly thing to fart at the moment, but otherwise if it smells I’m grossed out. 
I’m not sure why it’s funny, it just is. Unlike Demo, I don’t laugh when I’m by myself. For some reson that’s not funny. But, I do grade the smell on a scale of 1 to 10 even when alone. For more fart humor, check this site.
http://www.funstun.com/fart.htm
It doesn’t explain anything, but it’s immature and makes me laugh.