Source : Free On-Line Dictionary of Computing

vadding
     
         /vad'ing/ (From VAD, a permutation of ADV,
        i.e. {ADVENT}, used to avoid a particular {admin}'s continual
        search-and-destroy sweeps for the game) A leisure-time
        activity of certain hackers involving the covert exploration
        of the "secret" parts of large buildings - basements, roofs,
        freight elevators, maintenance crawlways, steam tunnels, and
        the like.  A few go so far as to learn locksmithing in order
        to synthesise vadding keys.  The verb is "to vad" (compare
        {phreaking}; see also {hack}, sense 9).  This term dates from
        the late 1970s, before which such activity was simply called
        "hacking"; the older usage is still prevalent at {MIT}.
     
        Vadding (pronounced /vay'ding/) was also popular {CMU}, at
        least as early as 1986.  People who did it every night were
        called the "vaders," possibly after "elevator," which was one
        of the things they played with, or "invader," or "Darth
        Vader".  This game was usually played along with
        no-holds-barred hide-and-seek.  CMU grad students were the
        known to pry open the inner doors of elevators between floors
        to see the graffiti on the inside of the outer doors.
     
        The most extreme and dangerous form of vadding is "elevator
        rodeo", also known as "elevator surfing", a sport played by
        wrasslin' down a thousand-pound elevator car with a 3-foot
        piece of string, and then exploiting this mastery in various
        stimulating ways (such as elevator hopping, shaft exploration,
        rat-racing, and the ever-popular drop experiments).  Kids,
        don't try this at home!
     
        See also {hobbit}.
     
        [{Jargon File}]
     
        (1996-01-07)