I stole this from a comment on youtube:
　

1. A Democracy: Three wolves and a sheep voting on dinner.

2. A Republic: The flock gets to vote for which wolves vote on dinner.

3. A Constitutional Republic: Voting on dinner is expressly forbidden, and the sheep are armed.

4. Federal Government: The means by which the sheep will be fooled into voting for a Democracy.

5. Freedom: Two very hungry wolves looking for dinner and finding a very well-informed and well-armed sheep....

The video from which the comment was... uhm... burrowed ;-) is here:
http://www.youtube.com/watch?v=0oV2mI0IYp8