Source : Free On-Line Dictionary of Computing

barney
     
        In Commonwealth hackish, "barney" is to {fred} as {bar} is to
        {foo}.  That is, people who commonly use "fred" as their first
        {metasyntactic variable} will often use "barney" second.  The
        reference is, of course, to Fred Flintstone and Barney Rubble
        in the Flintstones cartoons.
     
        [{Jargon File}]
     
        (1994-11-28)