I was thinking how it would be odd to have a programming language called en_AU.UTF-8.

There's a language called SLang inside Goldman Sachs used for their SecuritiesDB, and that's how I read it at first glance even with the dollar sign lol https://en.wikipedia.org/wiki/Michael_Dubno#SecDB

The $LANG programming language, where the keywords are all just in-jokes that change from week to week.

Likewise. Thought it'd be pronounced "slang", and thought the semantics would be you define LANG=<name of a language> at the top of the file (like a hashbang) and then write in whatever language you please. $LANG is a neato language because it has all the coolest features rolled into one unified design: polymorphic lifetime borrowing, endofunctor monoid monads, (stacked) coroutines, and even quantum data types.