People have always told me that you can't really understand a culture until you understand the jokes in that language...I now wholeheartedly agree.
I went out last weekend with an American friend and we met up with an Italian friend along the way. As we were heading home later in the evening, my American friend and I started telling jokes. We found them almost uncontrollably funny, but at some point realized that our Italian friend had not been laughing along with us. Turns out he didn't get the jokes, so we tried to explain them to him. After a lengthy discussion of the history, meaning, and hilarity of these jokes, he still looked skeptical and simply said, "I understand that the jokes are funny but I still do not understand why."
Which was to us, of course, hilarious.