Source : Free On-Line Dictionary of Computing

hacked off
     
         (Analogous to "pissed off") Said of {system
        administrators} who have become annoyed, upset, or touchy
        owing to suspicions that their sites have been or are going to
        be victimised by {crackers}, or used for inappropriate,
        technically illegal, or even overtly criminal activities.  For
        example, having unreadable files in your home directory called
        "worm", "lockpick", or "goroot" would probably be an effective
        (as well as impressively obvious and stupid) way to get your
        sysadmin hacked off at you.
     
        [{Jargon File}]
     
        (1996-08-26)