Source : Free On-Line Dictionary of Computing

metasyntactic variable
     
         Strictly, a {variable} used in {metasyntax}, but
        often used for any name used in examples and understood to
        stand for whatever thing is under discussion, or any random
        member of a class of things under discussion.  The word {foo}
        is the {canonical} example.  To avoid confusion, hackers never
        (well, hardly ever) use "foo" or other words like it as
        permanent names for anything.
     
        In filenames, a common convention is that any filename
        beginning with a metasyntactic-variable name is a {scratch}
        file that may be deleted at any time.
     
        To some extent, the list of one's preferred metasyntactic
        variables is a cultural signature.  They occur both in series
        (used for related groups of variables or objects) and as
        singletons.  Here are a few common signatures:
     
        {foo}, {bar}, {baz}, {quux}, quuux, quuuux...: MIT/Stanford
        usage, now found everywhere.  At MIT (but not at Stanford),
        {baz} dropped out of use for a while in the 1970s and '80s.  A
        common recent mutation of this sequence inserts {qux} before
        {quux}.
     
        bazola, ztesch: Stanford (from mid-'70s on).
     
        {foo}, {bar}, thud, grunt: This series was popular at CMU.
        Other CMU-associated variables include ack, barf, foo, and
        {gorp}.
     
        {foo}, {bar}, fum: This series is reported to be common at
        {Xerox PARC}.
     
        {fred}, {barney}: See the entry for {fred}.  These tend to be
        Britishisms.
     
        {toto}, titi, tata, tutu: Standard series of metasyntactic
        variables among francophones.
     
        {corge}, {grault}, {flarp}: Popular at Rutgers University and
        among {GOSMACS} hackers.
     
        zxc, spqr, {wombat}: Cambridge University (England).
     
        shme: Berkeley, GeoWorks, Ingres.  Pronounced /shme/ with a
        short /e/.
     
        {foo}, {bar}, zot: {Helsinki University of Technology},
        Finland.
     
        blarg, wibble: New Zealand
     
        Of all these, only "foo" and "bar" are universal (and {baz}
        nearly so).  The compounds {foobar} and "foobaz" also enjoy
        very wide currency.
     
        Some jargon terms are also used as metasyntactic names; {barf}
        and {mumble}, for example.
     
        See also {Commonwealth Hackish} for discussion of numerous
        metasyntactic variables found in Great Britain and the
        Commonwealth.
     
        [{Jargon File}]
     
        (1995-11-13)