What is a 'Post Turtle'?

My erudite friend, Michael Kirschenbaum, keeps sending me things that a) crack me up while b) making a lot of sense. Enjoy.

Post Turtle

While suturing a cut on the hand of a 75-year old Texas rancher whose hand was caught in a gate while working cattle, the doctor struck up a conversation with the old man. Eventually the topic got around to Sarah Palin and her bid to be a heartbeat away from being President.

The old rancher said, "Well, ya know, Palin is a post turtle."

Not being familiar with the term, the doctor asked him what a post turtle was.

The old rancher said, "When you're driving down a country road and you come across a fence post with a turtle balanced on top, that's a post turtle. You know she didn't get up there by herself, she doesn't belong up there, she doesn't know what to do while she is up there, and you just wonder what kind of dumb ass put her up there to begin with."