Aus

Can be used in many ways.

Originally a short way of saying "Australia", you're meant to use it as an adjective to describe Australian related things.
Can also be used to describe something that is upside-down.

Someone that feels like an "Aus" would be someone wearing a blue shirt, with the Australian flag on them.
They would tend to have brown hair and glasses as well. And despise upside down jokes.

Doctor: You've been diagnosed as an Aus..
Aus: What is that? is it bad?
Doctor: Yes it's pretty bad, however you get a free blue shirt with a flag on your way out.