Sometimes Say "Never"

Today's Quote of the Day inspires me to add my personal favorite, although I can't remember where I heard it:

"Never get on a horse named Cannonball."

Any others out there?

Edit: The QOTD has changed now, but Nelson Algren's recommendations were: "Never play cards with a man called Doc. Never eat at a place called Mom's. Never sleep with a woman whose troubles are worse than your own."