'A'
Ablution block Shower/toilet block at a camping ground 
Ace -that's- That is excellent
Aerial ping pong Australian rules football
Aggro -to be- To be upset or aggravated
Agots Testicles
Alberts Toe or foot rags worn by tramps or swagmen of low degree
Alf -to be an- To be a stupid person
All Blacks New Zealand Rugby Union footballers
All laired up Flashily dressed, dressed for some special occasion
All upper A punter who bets "all up" on a number of horse or greyhound races
All wet Silly, foolish
Alley A two-up school
Also ran A person who is a failure
Amber fluid Beer
Amster A trickster's confederate, a side-showman's decoy
Animal A contemptuous term for an objectionable person
Ankle biter A young child
Ant's pants -that is- That is top fashion
Anzac A member of the Australian and New Zealand Army Corps in World War I
Apple eater Anyone who lives in Tasmania
Apple Island Tasmania
Apples -she'll be- Don't worry, everything will be ok
Apron The neck fold of a merino ram
Argue the toss To dispute an order or a decision
Arm pit -that place is an- That place is terrible
Aroo Goodbye
Arse about face Something is back to front
Arse over tit -he went- He fell over
Arsey Lucky
Art Union A lottery in which the prizes are in kind, not money
Artichoke A debauched old woman
Artist One who indulges in excesses, eg "bull artist" "booze artist"
Arvo Afternoon
Auntie -don’t be an- Don't be stupid or silly
Aussie An Australian
Aussie rules The type of football known as Australian Rules
Aussieland Australia
Australian rules A code of football developed in the 1850s
Australian terrier A type of terrier first given recognition in 1909
Australites Small, smooth lumps of black glass, presumably meteorites
Australorp The utility type of Black Orpington fowl
AV Jennings marriage -ones- Refers to ones first marriage.
Awkward as a Chow on a bike Extremely awkward in behaviour. Chow = Chinaman
Awning over the toy shop -the- The male beer belly
Axle Grease An endearing name for Vegemite
Ay -?- I didn't hear what you said. Can you please repeat it?