The origin of foo & bar which almost everywhere in the demonstrating codes

The etymology of hackish `foo' is obscure. When used in connection with `bar' it is generally traced to the WWII-era Army slang acronym FUBAR (`Fucked Up Beyond All Repair'), later bowdlerized to foobar. (See also FUBAR.)
...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").
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Other sources confirm that `FOO' was a semi-legendary subject of WWII British-army graffiti more-or-less equivalent to the American Kilroy. ...
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.
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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 later became the MIT AI Lab was involved with TMRC, and probably picked the word up there.
Very probably, hackish `foo' had no single origin and derives through all these channels from Yiddish `feh' and/or English `fooey'.
Complete explanation can be found here.