Note $

Another recent (late 1990s) construction now common on Usenet seems to be borrowed from Unix shell syntax or Perl. It consists of using a dollar sign before an uppercased form of a word or acronym to suggest any random member of the class indicated by the word. Thus: ‘$PHB’ means “any random member of the class ‘Pointy-Haired Boss’”.

http://www.catb.org/~esr/jargon/html/writing-style.html