I would allow it.
The term foobar or foo and bar separately are very often used in programming examples, much like the Hello World program is commonly used as an introduction. foo is often used as a name for functions/methods and bar is commonly used for variable names.
Foo in the urban dictionary is most commonly used when someone is meaning the word fool. It has also been used when describing something that is not working the way someone thinks it should, or when something or someone is not "normal".
No. The word Zen is not allowed in Scrabble.
No. Jax is not a legal Scrabble word.
foo
Fumer (foo may)
You go to the foo mart go to breding supplies by used or new if you have foo dollars you can buy it new if you have only foo gems buy used. Then you have a litter license.
No, "hed" is not a word at all, and may not be used in Scrabble.
The Official Scrabble Dictionary lists lo as an acceptable Scrabble word. It is used to attract attention or to express surprise.
Yes. Ma is a Scrabble word.
No. Le is not allowed in Scrabble.
No. Zen is not a legal Scrabble word.