It's also a computer program for recording short, mildly amusing things that people say on zephyr, the CMU computer science department's electronic chat facility. Every time something is recorded, the program also responds with a previously recorded blurb. This page doesn't deal the gory details of how the program is used; for that, see the Cube FUCQ (though if you're not from CMU, there's not much point in looking at it).
It was also used to provide random initial responses to all questions posed to Forum 2000 (and its later incarnation Forum 3000), a humorous Q&A site that was a bit of a cult classic in the early days of the Web. Alas, the site no longer exists. At the time of this writing (late 2011), a mirror of its final state can be found here, including the Hall of Fame.
Here are a few things that even people outside CMU might find amusing:
Warning: the recorded material is occasionally R-rated, and often too technical to be understood and/or amusing to anyone other than serious computer geeks (and even then it's not always funny).