Inspired by This Thread, I would like to solicit, from all who dare, what you consider to be your favorite pun.
It can be chosen because you revere it as the best or simply because it makes you laugh out loud.
I have two stories in mind that I would be hard-pressed to choose (one over the other).
What have you got?

"I am certain there is too much certainty in the world" -Michael Crichton