A rationalist and a christian argue about the existance of god. When the rationalist is bored he finally says: "Listen, the probability of god existing is about as small as winning the lottery, so if you win the lottery next week we can talk." They meet again next week and the christian did in fact win the lottery so the rationalist says: "Yeah, I calculated it again and it's more like winning the lottery twice." The week after they meet again and much to the horror of the rationalist the christian won the lottery a second time. He doesn't know what to answer so they part again and meet again the third week. The rationalist says: "Well, the probability of that happening was insignificantly small, so I think I need to update my beliefs and acknowledge the fact that there might be a god." Says the christian: "Well, I just realized I am rich now. I don' think I believe in god anymore."
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:
Edit (April 12th): The winner of the corny rationalist joke contest is this one-liner by SilasBarta, which collected 17 net up-votes:
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.
Thanks to everybody who contributed and voted on corny jokes.