Source : Free On-Line Dictionary of Computing

borf
     
         To uncerimoniously disconnect someone from a system
        without prior warning.  {BBS} {Sysops} routinely "borf" pest
        users by turning off the modem or by hitting the "auto-borf"
        key sequence.
     
        You can also be "borfed" by software dropping {carrier} due to
        a {bug}.
     
        The origin of the term is unknown but it has been in use since
        at least 1982.
     
        (1997-03-21)