There are a lot of things that make me laugh. And a lot of them I would not have a problem explaining to others why I find them so funny. Then there are things that I can't believe I still giggle so much everytime I hear it.
One example of this is an old joke I heard on Conan. I don't remember the set up, I just know the punchline was "Clay Aiken-for-man-sausage." Such a stupid joke, and yet it still cracks me up whenever I think about it.
Another thing I found absolutely hilarious that no one ever understood was when I had cable and there were two tv channels that would play the same programming about 3 seconds apart. I would watch 3 seconds of one, and flip to another channel to see it repeated and it was hours of endless comedy that I don't think makes any sense.