Wiktionary
n. (context colloquial AU NZ and nautical English) A cigarette break from work or military duty; a brief cessation of work to have a smoke, or (more generally) to take a small rest, snack etc. (from 19th c.)
Wikipedia
"Smoko" (also "smoke-o" or "smoke-oh") is a term used in Australian English, New Zealand English and Falkland Islands English for a short, often informal, cigarette break taken during work or military duty, although the term can also be used to describe any short break such as a rest or a coffee/tea break. Among sheep shearers in Australia, "smoko" is a mid-morning break, between breakfast and lunch, in which a light meal may be eaten. Within New Zealand the term has generally altered to include coffee breaks and outdoor rests. The term is used primarily in New Zealand amongst the building and manufacturing communities.
The term is believed to have originated in the British Merchant Navy, and was in use as early as 1865. The term is still in use in the British Merchant Navy today. The tradition of a smoko in the Australian sense seems to have begun amongst sheep shearers in the 1860s.
Although a slang term, the word "smoko" has been used in government writing and industrial relations reports to mean a short work break.
Usage examples of "smoko".
It said only that they were loading the trucks and would be back for smoko later that morning, and she sighed.
Cold meat and bread will be enough for lunch, but the men like something sweet for smoko in the mornings and afternoons.
An inspection of the storeroom had revealed the wherewithal to make not only a chocolate cake for afternoon smoko but flapjacks as well.
Clare could imagine them all stopping for smoko, Joe rolling his cigarette, Ben greedily eating biscuits, Gray drinking his tea, quiet and contained as always.
She rang when the men were having smoko, and got through almost straight away.
Bruce watched the rural delivery agent stop at his letterbox from the hill above the house and decided that it was time for morning smoko.