It changes and evolves. Fair dinkum is still in use, though it's probably diminishing. Australian slang today is still uniquely Australian, natch, but a lot of "traditional" Aussie slang has passed into jokey stereotypical speak to confuse foreigners. A few examples of contemporary Aussie slang would include goonsack, maggot (an adjective), arvo, woop woop, and bogan. The word "rort" is a rare example of a word unique to us that is often used in formal language.