I have an extra copy of Richard Feyman's autobiography, "Surely You're Joking, Mr. Feynman!": Aventures of a Curious Character, which I want to give away here.

This is one of two autobiographies (along with Ben Franklin's) to actually change my life.  I've seen it quoted often on LessWrong, as Feynman has a point of view on life that fits well with the ideas we explore here.  In addition to his rationalist side, Feynman also exhibited a wonderfully free sense of humor. Even when working at the Manhattan Project, he joked around and never took himself too seriously.  I think our community would benefit if the rationalism here were likewise leavened by some self-deprecating humor.

I will mail the autobiography, at my expense, to whomever posts the best corny rationalist joke in the comments below, as judged by karma voting.  Anything goes.  Here's a little inspirational prompting:

• How many rationalists does it take to screw in a lightbulb? ...
• Two rationalists walk into a bar. ...
• You might be a rationalist if ...

Edit (April 12th): The winner of the corny rationalist joke contest is this one-liner by SilasBarta, which collected 17 net up-votes:

Rationalist pick-up line: "I would never cheat on you if and only if you would never cheat on me if and only if I would never cheat on you."

The runner-up (and my personal favorite) is this exchange by Bo102010, which collected 14 net up-votes.   The full comment thread for this one has an explanation and suggested refinements.

A rationalist walks into a bar with two bartenders. The rationalist asks "What's the best drink to get tonight?"

The first bartender says "The martini."

The second bartender says "The gin and tonic."

The first bartender repeats "The martini."

The second bartender repeats "The gin and tonic."

The first says again "The martini."

The second says again "The gin and tonic."

Then the first says "The gin and tonic."

The rationalist smiles and says, "I'm glad you could come to an agreement."

Thanks to everybody who contributed and voted on corny jokes.