What's the meaning and origin of the Australian slang "fair dinkum"?

ill give yu a short one

we usually say it as in "you serious mate?" or "its true" when sum1 doesnt beieve you like
"fair Dimkum the roo was 6 ft"

Helpfull??

The story I heard was that it came from the Chinese gold miners. During the gold rush, booze was paid for with a pinch of gold. The miners paid for drinks with a pinch of gold and if the measure wasn't enough, the miners used the term "fair drinkin'" which meant "fill it up" the Chinese copied with "fair dinkum". So that's another version of the origin of the term. The Chinese have never been shy of drinking and that is still reflected today. The drinks at Chinese restaurants are always more than a standard measure.

According to stereotype, spoken Australian English is thought to be highly colloquial, possibly more so than other spoken variants. Whether this idea is grounded in reality or not, a substantial number of publications aimed at giving an overview of Australian English have been published.

Many books about Australian vocabulary have been published, beginning with Karl Lentzner's Dictionary of the Slang-English of Australia and of Some Mixed Languages in 1892. Several similar books soon followed, including a relatively modest but authoritative work by E. E. Morris: Austral English: A Dictionary of Australasian Words, Phrases and Usages (1898).

After a long period of disinterest and/or antipathy, the first dictionaries of Australian English began to appear. In 1976, the Australian Pocket Oxford Dictionary was published, the first dictionary edited and published in Australia, by Graeme Johnston. In 1981, the more comprehensive Macquarie Dictionary of Australian English was published, after 10 years of research and planning. Updated editions have been published since and the Macquarie Dictionary is widely regarded as authoritative. A fuller Oxford Dictionary of Australian English has also been published.

Various publishers have also produced "phrase books" to assist visitors. These books reflect a highly exaggerated and often outdated style of Australian colloquialisms and they should partially be regarded as amusements rather than accurate usage guides.
A common feature of traditional Australian English was rhyming slang, based on Cockney rhyming slang and imported by migrants from London in the 19th century. Rhyming slang consists of taking a phrase, usually of two words, which rhymes with a commonly used word, then using the first word of the phrase the represent the word. In recent years this feature of Australian English has declined under the impact of mass popular culture.
Australians use a variety of colourful terms to refer to people. These terms may indicate such things as the person's ethnicity, the place where the person resides, the social status of the person, the person's behaviour, etc. Many of these words occur in other English dialects, especially New Zealand English, whilst others are unique to Australian English.
Hope I Helped!

The origin of fair dinkum is from the goldrushes in the 1800s in Australia. Chinese gold miners used to describe gold as "din gum" meaning "real gold" in Chinese. It means that it is the absolute truth, completely genuine. You can also just say "dinkum", meaning authentic.

So you might say, "fair dinkum, I won the lottery yesterday."

But I've noticed that most people in Australia lately have been using it like you would "you're joking".

Well I'm astounded. I don't know the exact origin of the phrase "fair dinkum" either, that's why I punched it into Google to find out.

However, I thought I had a hazy, but correct, idea of the origin, because I was told it either at school or at Glasgow University, where I studied English in the late 60's. That's why, when I used Google to research the phrase, I didn't enter "fair dinkum". I entered what I remembered I was taught to be the correct original phrase, which was "fared income".

I said it was a hazy memory of what I was taught, but it related in some way to variations of the connotation of the word "true". True, upright, honest, etc. But the phrase which seems to link best, in this context, is "someone who pays his way". This gels with the stereotypical Aussie view of life, and people. Aussies like people who "tell it like it is". That's where I think people trying to derive the origin of the phrase go wrong, because they just accept the "fair" part of the expression (because it sounds logical and "Aussie-like"), and leap to rationalise the apparently inexplicable "dinkum" part.

As I said, I can't quite remember the exact derivation now (maybe it'll come back after a while), but you can speculate as well as I can about the context of those two words "fare" ("fared" being an adjective from the noun "fare"), and the noun "income".

Given the nature of the original process(es) of populating Australia, it's not difficult to think of an alternative phrase to "paying your way" being "working your passage". I'm thinking of a current meaning of "fare" as "the price of a ticket to travel". So you could pay your fare from the income received by working on the journey, or "working your passage". Someone who did this could be said to be receiving "fared income" - income turned into a fare.

So it's easy to see why this behaviour could be referred to as "fared income", and that someone who had done this could be called a "fared income" person. All the other connotations follow easily.

Given that many of those early Australians would be British, and Britons love corrupted abbreviations, the corruption to a "fair dinkum" person is easy to see.