1. Australian English incorporates several uniquely Australian terms, such as outback to refer to remote regional areas, walkabout to refer to a long journey of uncertain length and bush to refer to native forested areas.
2. Fair dinkum can mean are you telling me the truth?, or this is the truth!, or even this is ridiculous! depending on context. G'day is well known as a stereotypical Australian greeting. (It is worth noting that "G'day" is not quite synonymous with "good day", and is never used as an expression for "farewell".)
3. Some elements of Aboriginal languages have been incorporated into Australian English, mainly as names for places, flora and fauna (e.g. Dingo, kangaroo). Beyond that, very few terms have been adopted into the wider language. A notable exception is Cooee (a musical call which travels long distances in the bush and is used to say 'is there anyone there?'). Though often thought of as an Aboriginal word, Didgeridoo/Didjeridu (a well known wooden musical instrument) is actually an onomatopoeic term coined by an English settler.
4. Australian English has a unique set of diminutives formed by adding -o or -ie to the ends of (often abbreviated words). There does not appear to be any particular pattern to which of these suffixes is used. Examples with the -o ending include abo (aborigine - now considered very offensive), arvo (afternoon), servo (service station) and ambo (ambulance officer). Examples of the -ie ending include barbie (barbeque), bikkie (biscuit) and blowie (blowfly). Occasionally, a -za diminutive is used, usually for personal names. Barry becomes Bazza, Karen becomes Kazza and Sharon becomes Shazza.
5. A substantial collection of unusual words are in common spoken usage - e.g. "dacks" (trousers), "dag" (unfashionable person), "ute" (a utility truck). An even larger vocabulary is derived from recognisable words with entirely new meanings - "to bag" (to criticise), "blue" (either a fight or heated argument, or an embarrassing mistake), "crook" (unwell, also unfair), "to wag" (to play truant), "cactus" (non-functional), "cut" (angry) and especially "root" (a euphemism for sexual intercourse, which has caused social embarrassment for American women who innocently declare that they "root" for a particular sports team). Iin Australia fanny is a slang term for a vagina.