I never claimed I was terribly mature.

https://en.wikipedia.org/wiki/Foo_Pass

[1] https://en.wikipedia.org/wiki/Metasyntactic_variable#Italian

I've seen foo, bar, baz, qu+x, plugh and xyxxy actually in use, not the others.

I've not used "qux" or followed the convention of adding more u's. From me it's been just foo, bar, baz, quux and then some Monty Python inspired ones: spam, ni, ecky, ptong.

Although eventually I learned enough about how to name things that I don't feel the temptation any more. I'll gladly pay that bit of joylessness to understand myself months later.

my advice to junior programmers after i see them agonising over a name - "just call it x or foo for now, you are going to change it later anyway"

i first heard "foo bar" from eric allman at berkeley office of britton-lee, mid 1980s. i vaguely recall eric wrote a column about history of "foo bar".