jargon.artrocity.com
New Hacker's Dictionary the Jargon File v 4.4.6
A bug in a public software release that is so embarrassing that the author notionally wears a brown paper bag over his head for a while so he won't be recognized on the net. Entered popular usage after the early-1999 release of the first Linux 2.2, which had one. The phrase was used in Linus Torvalds's apology posting.