A couple weeks ago my Aussie housemates enlightened me to the phrase 'sticky beak', which means the same as the English phrase 'sneaky peak'.
It's pretty clear what's happened here:
A traveller (let's make him male) once came to England and picked up the phrase 'sneaky peak'.
When it became time to return home the journey was so long (this was before planes), he began to forget the phrase.
When he finally returned to Australia he got in to a conversation...
I imagine it went a bit like this:
"Ah mate, g'day"
"Bin' a whiale eint it mate"
"Yih, it'as. Hey did yah 'ere about the Barbie t'night"
"Nah i din't mate"
"Yih, Barbie t'night mate. Was a big off croc in me garden yesterdih mate - So i shot it and me Sheila said it'd be great on the Barbie"
"Nice one mate, how big we talkin"
"I'd 'av t'say a good 2 miters mate - it's jus over thir under me human siyze koala"
"Ahhh mate, let's 'av a...."
And this is where he stumbled searching for the phrase.
"Sticky beak? I like it mate - niyce phrase"
"Thanks mate, those English 'av tonnes of 'em"
"Yih, 'af to start using that one mate - impress the Sheila's y'know"
Before you know it, the term 'sticky beak' has spread as fast as the news of a discounted beer across the whole of Australia!
I'm sure this happens more often than you'd think worldwide and i'd support it with more examples, but it's a Friday and my brain's pretty much shut down.
*This may not be factual or supported by any real evidence
*But it's still true