I just whacked my funny bone and oww did it hurt. Since I had just done the "Fun French words" section of this blog, I realized I didn't know how to say "funny bone" in French. None of us are actually Franco-French in my house, and I can't say it would normally come up in a conversation.
So I looked it up on WordReference (which by the way is a great resource), and it said that the informal translation was le petit juif (the little Jew). As in (this is the example given), "I accidentally hit my little Jew and my arm is still tingling." I think I'll be using le nerf ulnaire instead.