Definitely not an Aussie expression. Came from a Yugoslavian bodybuilder competing in Sydney. He used to do handstands in his routines. When asked why he said he wanted to show people that bodybuilders were not muscle bound. Every contest after that people yelled out "handstand" and Jehova would do it and everyone laughed. The Aussies encourage such people. When I talked to him one day he said, "What you?" Hard to translate but what about you, what have you done, etc. I have a few people who laugh when I say it because it can make heaps of things amusing.
There you are, what you!