Metasyntactic variables are so called because (1) they are variables in the metalanguage used to talk about programs etc

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 (thanks largely to early versions of this lexicon!). 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 gorp.

foo, bar, bletch: Waterloo University. We are informed that the CS club at Waterloo formerly had a sign on its door reading "Ye Olde Foo Bar and Grill"