Source : Free On-Line Dictionary of Computing

foo
     
         /foo/ A sample name for absolutely anything,
        especially programs and files (especially {scratch files}).
        First on the standard list of {metasyntactic variables} used
        in {syntax} examples.  See also {bar}, {baz}, {qux}, {quux},
        {corge}, {grault}, {garply}, {waldo}, {fred}, {plugh},
        {xyzzy}, {thud}.
     
        The etymology of "foo" is obscure.  When used in connection
        with "bar" it is generally traced to the WWII-era Army slang
        acronym {FUBAR}, later bowdlerised to {foobar}.
     
        However, the use of the word "foo" itself has more complicated
        antecedents, including a long history in comic strips and
        cartoons.
     
        "FOO" often appeared in the "Smokey Stover" comic strip by
        Bill Holman.  This surrealist strip about a fireman appeared
        in various American comics including "Everybody's" between
        about 1930 and 1952.  FOO was often included on licence plates
        of cars and in nonsense sayings in the background of some
        frames such as "He who foos last foos best" or "Many smoke but
        foo men chew".
     
        Allegedly, "FOO" and "BAR" also occurred in Walt Kelly's
        "Pogo" strips.  In the 1938 cartoon "The Daffy Doc", a very
        early version of Daffy Duck holds up a sign saying "SILENCE IS
        FOO!".  Oddly, this seems to refer to some approving or
        positive affirmative use of foo.  It has been suggested that
        this might be related to the Chinese word "fu" (sometimes
        transliterated "foo"), which can mean "happiness" when spoken
        with the proper tone (the lion-dog guardians flanking the
        steps of many Chinese restaurants are properly called "fu
        dogs").
     
        Earlier versions of this entry suggested the possibility that
        hacker usage actually sprang from "FOO, Lampoons and Parody",
        the title of a comic book first issued in September 1958, a
        joint project of Charles and Robert Crumb.  Though Robert
        Crumb (then in his mid-teens) later became one of the most
        important and influential artists in underground comics, this
        venture was hardly a success; indeed, the brothers later
        burned most of the existing copies in disgust.  The title FOO
        was featured in large letters on the front cover.  However,
        very few copies of this comic actually circulated, and
        students of Crumb's "oeuvre" have established that this title
        was a reference to the earlier Smokey Stover comics.
     
        An old-time member reports that in the 1959 "Dictionary of the
        TMRC Language", compiled at {TMRC} there was an entry that
        went something like this:
     
        FOO: The first syllable of the sacred chant phrase "FOO MANE
        PADME HUM."  Our first obligation is to keep the foo counters
        turning.
     
        For more about the legendary foo counters, see {TMRC}.  Almost
        the entire staff of what became the {MIT} {AI LAB} was
        involved with TMRC, and probably picked the word up there.
     
        Another correspondant cites the nautical construction
        "foo-foo" (or "poo-poo"), used to refer to something
        effeminate or some technical thing whose name has been
        forgotten, e.g. "foo-foo box", "foo-foo valve".  This was
        common on ships by the early nineteenth century.
     
        Very probably, hackish "foo" had no single origin and derives
        through all these channels from Yiddish "feh" and/or English
        "fooey".
     
        [{Jargon File}]
     
        (1998-04-16)