Source : Free On-Line Dictionary of Computing

asbestos longjohns
     
         Notional garments donned by {Usenet} posters just
        before emitting a remark they expect will elicit {flamage}.
        This is the most common of the {asbestos} coinages.  Also
        "asbestos underwear", "asbestos overcoat", etc.
     
        [{Jargon File}]
     
        (1997-07-04)