As per usual, that’s British slang which was carried over to Australia. Almost all slang phrases Americans associate with Australia are British in origin and still in wide use, as you’d expect given the history of both countries.
It's also commonly used in the US. I've never heard it of it being associated with the commonwealth at all - based on the vulgarity I always assumed it was a native production.
As an Australian, I can confirm that basically everything about Australian culture (good and bad) is just British, sometimes with a little twist.
I did not know that was an Aussie thing (heard in England often enough)
My favourite is “Going off like a frog in a sock”
But there are many to choose from. “Face like a dropped pie” is another gem.
While I can understand this for muscular guys, I never got why it can also be used to mean a very curvaceous/attractive woman.
>I never got why it can also be used to mean a very curvaceous/attractive woman.