/hyü-mər ha-kər/
n. A distinctive style of shared intellectual humor found among hackers, having the following distinctive characteristics:
1. Fascination with form-vs.-content jokes, paradoxes, and humor having to do with confusion of metalevels (see meta). One way to make a hacker laugh: hold a red index card in front of him/her with "GREEN" written on it, or vice-versa (note, however, that this is funny only the first time).