XPEX was a parody summary that (as Alan points out) came to us after many rounds of Guinness in the Hotel lobby (somewhere right after Alan declared that XP needed a Flag if it were to conquer the world, if I recall correctly).
There's a lot of in-jokes of course (some very dated to the conference), but a lot of more general pop culture and Extreme Programming community references. For fun, see how many you can find.
Big thanks to Alan for resurrecting this. I needed a brief light moment before I dive back into the crazy rewrite/refactoring that has been my sole focus for the past two weeks.