The Three Kinds of Economist Jokes

I've been working, with my Duke colleague Geoffrey Brennan, on a paper on "economist jokes." We are trying both to catalog and to explain the phenomenon of economist jokes. (If you know any good ones, please do send them along!) Here I will summarize the reasons we have come up with to explain why economist jokes exist, and to give an example of each of the three "types" of economist jokes that we have identified.