And here is another really great one doing the rounds on the net.

   While suturing a laceration on the hand of a 90-year-old man,
   the doctor asked his patient how he thought George W. Bush was
   doing as President.
   
   The old man said, "Ya know, Bush is a post turtle." Not knowing
   what the old man meant, the doctor asked him what a "post
   turtle" was.
   
   He said, "Did you ever drive down a country road and come across
   a fence post with a turtle balanced on top? You know he didn't
   get there by himself, he doesn't belong there, he can't get
   anything done while he's up there, and you just want to help the
   poor thing down. That's a post turtle."