How would you use “Fair dinkum?”
I’m pretty confident that won’t be picking up “ta” anytime soon.
I’ve never heard either variation.
It can be used to emphasise a statement:
Or to stress that one’s information is credible:
Or in the interrogative, to question the veracity of a statement:
I’ve lived in BC for decades and the phrase has been in common usage here for about 10 or 15 years.
It looks to me like “Fair dinkum” could be replaced by the word “Really,” although with different emphases, in each of your examples, Cunctator. Would that be fair to say?
Fuhgeddaboutit.
It’s an assertion of veracity, which has functionally drifted slightly in meaning in other situations. It can be engaged in an insult to an idiot in a bar who has just spilt beer on you: “Fair dinkum, mate, you are a complete and utter dickhead!” (be ready to fight after this). “Really” works as a substitute in many cases as a rough translation of meaning but doesn’t convey the flavour of the expression and wouldn’t work as a simple substitution.
Yeah, the exceptions would be where “fair dinkum” is being used in a fashion more similar to “the real McCoy”.
Ditto NZ. 'No worries" and “No problem” are likely responses. In NZ at least people use “No worries” / “No problem” in the fashion of “de nada” – “it is nothing” / “think nothing of it”.
Although I can’t recall where I read it, I do remember someone being quite put out by a waiter replying “no problem” instead of “you’re welcome” to a customer’s thanks – the customer seemed to feel that of course it wasn’t a problem, since it was the waiter’s job, and that the response was impolite. 
There was a long Pit thread about this issue a few years back. There’s a lot of stupidity in that thread from people who see “No problem” as somehow offensive or dismissive.
In my experience, it tends to be older people - my mom among them - who think “No problem” is a less polite response than “You’re welcome.”
I didn’t mean to suggest that, in ordinary Australian idiomatic conversation, “Really” would always be substitutable for “Fair dinkum” - just that it has the same basic meaning.
Ahh… retail not waiter, but yes, that’d be the conversation I was thinking of. 
Yes, same basic meaning… and if extended to “real” or “true” then I guess it even covers the “real McCoy” meaning.
“Rudd says ocker sound bites fair dinkum” (ABC News headline).
My grandfather who would be about 120 now if he was alive used no worries, so it seems to go back a fair way down under and it really is great term.
No worries means don’t stress mate.
But sad to day we don’t hear cobber much anymore or someone calling dinner “tea”.
The only time I hear anyone saying fair dinkum it’s a comically out of touch politician trying to show empathy with the common man in the street. Such politicians may also take to wearing cowboy hats with their conservative business suits.
No one else has used it since the 1950s.
Here’s one of the fellows now…
“Good on ya” is indeed an Australianism, but when I’m talking to my US friends, I say “good for you” so I’ll be understood. Interesting to see your comment that “good on ya” is popping up there - now I can relax and use the term that comes naturally to me!
<shudder> I wish you’d put a warning up about that pic.
That’s NSFW! 
John Howard: the man who wanted to have “mateship” written into Australia’s constitution! :rolleyes:
An Australian friend of my mother-in-law, whom I stayed with a couple of weeks ago near Sydney, frequently uses “you-beaut-fair-dinkum” as an intensifier. She’s in her 60s, and yes she does it in a slightly knowing way, but people do still use it.
I didn’t read the whole thread but that is a different use to how it is use in Australia.
“It means no worries for the rest of your days”
is like saying “It means no bills for the rest of your days”
I don’t think the song is saying “It means “no worries”, for the rest of your days”