Prisoner of Bill
(PoB) A derisory term, in use generally among Unix users, for anyone who uses Microsoft products either because they don't know there is anything better (i.e. Unix) or because they would be incapable of working anything more complex (i.e. Unix).
The interesting and widespread presumption among users of the term is that (at least at the time of writing, 1998) using anything other than Unix or a Microsoft OS (whether VMS, Macintosh, Amiga) is so eccentric a choice as to be at least somewhat praiseworthy.