Leopards

Language Log is almost always interesting and often entertaining, but the following snippet, by Geoffrey Pullum, tickles me for some reason:

You can't get a leopard to change his spots. In fact, now that I come to think of it, you can't really get a leopard to appreciate the notion that it has spots. You can explain it carefully to the leopard, but it will just sit there looking at you, knowing that you are made of meat. After a while it will perhaps kill you.