All an outsider needs to know about the strange Aussie two-up ritual

Some would put ten dollar bills on their heads and shout, "Heads!"

It would clearly need the most skilled anthropologist to decipher this. Forget ancient rituals deep in the jungles of Borneo but this, it seemed, was truly strange.

"Ah, that's two-up", Aussies explained as though any British fool would know. "Two-up, mate. Anzac Day."

Ah, yes - but none the wiser.

But then I asked true blue Australians what the rules actually were - and, do you know what, they didn't actually know.

"It's about throwing coins in the air, and there's betting and there's heads or tails, and a 'boxer' and a 'ringer' and a 'kip'. And there are two coins or is it three?"

The truth is that Australians revere this distinctly - uniquely - Australian pastime, available on one day of the year, but hardly anybody knows the actual rules.

So as a public service to ridgy-didge Australians, here's what two-up seems to involve.

Firstly, two-up often uses three coins. That's because the result depends on two coins coming up heads or tails - two of the three if it's three coins; both if it's two.

So the betting is on heads or tails. The odds are 50:50. You won't walk away with a fortune unless you bet a fortune. The odds on you winning enough to pay off the mortgage are slim to nil.

There's a person in the middle of a "ring" (which can be square) who spins old pennies in the air. Old pennies were used by diggers in both world wars and they have weight, too, so they don't drift in a wind.

They seem to be able to pause in-flight, giving that frisson of expectation. New fangled money doesn't cut it.

The person in the middle is called the "spinner" because, well, he spins the pennies, and he does that with his "kip" or short wooden paddle board (don't ask).

People in the crowd bet in an increasingly raucous way. As the beer goes down, the bets go up.

One punter might shout, "$10 on heads", and another across the square ring will match the bet on tails. In some places, apparently, the person with money on heads will actually put money on their head. Amazing.

The person betting on heads holds the money while the coins spin. Whoever calls it right keeps the $20.

But don't bank on paying off your student debt or buying another Harley (or Tesla if you must).

The point is the ritual. It's part of coming together.

It was made legal only on Anzac Day in the '80s. "It was widely regarded as the fairest of gambling games," according to Bruce Moore of the ANU who wrote Come in Spinner: A History of Two-Up and its Language.

"At the time of the First World War, the verbal command for the coins to be spun was not 'come in spinner' (as it is now) but 'fair go'. Indeed, the important Australian concept of the 'fair go' was in part cemented by its role in the game.

"Two-up is a ritual that links the present with the past on this one day of the year."