For about 6 months back in about 1988 I went about the place telling people a joke:
Q. Why did the mushroom go to the party?
A. Because he was a fun guy.
One of the funniest things about this, according to my wife anyway, was that I didn't actually get the joke for that entire period, and when I did, I stopped telling it.
I just thought it was an experiment in surrealism, and when I realized it wasn't, it lost all appeal for me.