Australian English like all other languages being used is a living entity and is constantly changing. Many slang terms used by my parent's generation are infrequently used now. Likewise, the language used by Aussie teenagers today is different from the language I feel comfortable using.
With the internet, television and the globalisation of almost everything, cultures are being influenced by other cultures and many slang terms are now almost universal.
However, we do need to take care when we use language in different cultures, because even the same slang terms can mean different things. Two examples which come to mind are the words "thong" and "fanny". These words have very different meanings in the United States of America and in Australia.
In Australia, the context in which various words are used can totally change the meanings of those words. An example is the word "bastard". The dictionary meaning is "a person born from an unmarried mother". It is used in a derogatory sense in most cultures and can be used that way in Australia also. However, in Australia it can also be used in an almost affectionate way between good friends.