Source : Free On-Line Dictionary of Computing

obi-wan error
     
        /oh'bee-won" er"*r/ [RPI, from "off-by-one" and the Obi-Wan
        Kenobi character in "Star Wars"] A loop of some sort in which
        the index is off by 1.  Common when the index should have
        started from 0 but instead started from 1.  A kind of
        {off-by-one error}.  See also {zeroth}.