Isn't it supposed to be fubar? fucked up beyond any recognition?

Yes that’s the original spelling & meaning. But using the spellings foobar, foo, bar, and sometimes baz, have been used for decades in programming as examples, temporary names, stand-ins etc. I just assumed that spelling it foo was meant to distance it from the curse word slightly while simultaneously making the pronunciation more clear (i.e. foo not fuh); foo just makes a good nonsense word.

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

not in code, the tradition has been two words actually, foo and bar