jargon.artrocity.com
New Hacker's Dictionary the Jargon File v 4.4.6
[perverted from mathematical jargon] An expression used ironically to characterize unquantifiable behavior that differs from expected or required behavior. For example, suppose a newly created program came up with a correct full-screen display, and one publicly exclaimed: “It works!” Then, if the program dumped core on the first mouse click, one might add: “Well, for suitably small values of ‘works’.”