The word cooee comes from Aboriginal tribe known as the Darug who originally occupied the land that most of modern Sydney is built on. The word means come here, and when done properly, the sound can cover quite a long distance. It is especially fun to do in an environment where there is a good echo.
The title is fun to say. I have no idea what it means, but it's fun to say. Thanks for sharing!
I wouldn't say that it is a word that is in common usage in modern Australia, but it is fair to say that it is pretty much irresistable to give a few coo-ees if you find yourself in the bush, or up a mountain!
Here's an example of how it is done.