jargon.artrocity.com
New Hacker's Dictionary the Jargon File v 4.4.6
(also logical Friday) The last day before an extended weekend, if that day is not a ‘real’ Friday. For example, the U.S. holiday Thanksgiving is always on a Thursday. The next day is often also a holiday or taken as an extra day off, in which case Wednesday of that week is a virtual Friday (and Thursday is a virtual Saturday, as is Friday). There are also virtual Mondays that are actually Tuesdays, after the three-day weekends associated with many national holidays in the U.S.