The Aussie reference article from the English Wikipedia on 24-Jul-2004
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Aussie

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"Aussie" is friendly slang for "Australian". The correct pronunciation is "O-zee", SAMPA: ["Qzi]. Pronouncing the word with the unvoiced "s" in place of the voiced "z" is strongly frowned upon by Australians, and is considered a canonically North American error, along with such errors as pronouncing the last syllables of Melbourne and Brisbane as the words "born" and "bane". (Both are correctly pronounced with a schwa.)

As well as referring to Australian persons, the term is used with patriotic gusto in sporting chants. The most widely used is probably

Aussie Aussie Aussie! Oi oi oi!
Aussie! Oi! Aussie! Oi!
Aussie Aussie Aussie! Oi oi oi!
The phrases in bold are shouted in response to a single person leading the cheer. The first line may be or may not be doubled. Volume is important.

Dog owners also use the term to refer to the Australian Shepherd.