Source : Free On-Line Dictionary of Computing

twirling baton
     
         The overstrike sequence -/|\-/|\- which produces an
        animated twirling baton.  If you output it with a single
        backspace between characters, the baton spins in place.  If
        you output the sequence BS SP between characters, the baton
        spins from left to right.  If you output BS SP BS BS between
        characters, the batton spins from right to left.
     
        The twirling baton was a popular component of animated
        signature files on the pioneering {PLATO} educational
        {time-sharing} system.  The "{archie}" {Internet} service is
        perhaps the best-known baton program today; it uses the
        twirling baton as an idler indicating that the program is
        working on a query.
     
        [{Jargon File}]
     
        (1995-02-23)