It originally started as shorthand for ‘a smoking break’.
These days its meaning is a lot broader to the extent it basically covers any short break from work.

Believe it or not, it even appears in Australian legal documents.
For example:

 …regarded as a Friday shift.
<
(e) Smoko Break - A paid 15-minute smoko break shall be allowed to all
+ employees covered by this award once each shift, Monday to Friday. T
+he employees shall take the break in a crib room at a time mutually a
+greed upon between the employer and the employees. The procedure for 
+Australian Workers' Union employees shall be as contained in an excha
+nge of letters between the parties.


(f) Rostered Day Off - The employer…
[download]

..and I think the word you're looking for is ‘Strine’.

As in "'Strine maayte. You Know? From 'Straya.".

I've always thought it sounded more like 'Striyne' myself but it's hard to replicate the atomically small hints that some Australians can give to vowels.

Anyway, as all this hard yakka won't be wortha brass razoo to a bunyip for my experience points, I'll be hitting the frog'n'toad me china plate.

PS: Double points for any translations from people originating outside of the south pacific who don't stuff up on the term 'Hard Yakka'.