They are as Australian as kangeroos, the Sydney Opera House and vegemite but phases like fair dinkum and drongo are on the banned list for certain Aussie troops.
Australian soldiers have been banned from using slang while they are training with US Marines.
The rationale, according to Air Force Group Captain Stewart Dowrie, is that slang can lead to confusion on the battlefield.
Over 1700 US Marines are currently training with Australian troops in Darwin, and the differences between the way the two sets of soldiers speak have been causing problems.
"Classic phrase 'lucked out' -- for some people it means you get lucky, for others it didn't happen," Dowrie told 10 Daily.
"So you start using colloquialisms and all of a sudden you have complete misunderstandings about whether something is going to happen."
He says military training scenarios use "very prescriptive means of communication".
"It is important that we get in that same room, stare at each other across that same room and actually understand how we use the English language," he told 10 Daily.
"Even between the Australian and the US we actually mean slightly different things."
In case of any confusion, here are eight Aussie words the US Marines might struggle to understand:
Root sexual intercourse
She'll be right it will be okay
Stubbie beer bottle