Across the country on Anzac Day, pubs and RSLs will be packed full of Aussies revelling in a mid-week public holiday and a chance to play a game that's only legal once a year - two-up.
The popular gambling game is technically illegal on most other days of the year.
Two-up first originated in the early 1800s and was popular among poorer English and Irish people.
It made its way to Australia with the arrival of the First Fleet, spreading widely across the country following the Gold Rush.
The game was a hit amongst Aussie soldiers fighting overseas, who were looking for a fun way to pass the time with limited resources.
When the soldiers returned from battle, two-up soon became a regular fixture at many RSL clubs and pubs and a popular game of choice for diggers when celebrating Anzac Day.
Even though the game was hugely popular in these licensed venues, it was still illegal.
Most police and law enforcement authorities would turn a blind eye to this sort of gambling, but over the past few decades some of the states and territories tightened their rules, only allowing two-up to be played on Anzac Day, with a few rules attached.
For example, Victoria's Gambling Regulation Act states the RSL must provide permission for every game of two-up played, and insists all profits go straight to Anzac Appeal, a charity that benefits Aussie veterans.
In New South Wales, there's actually a special law called The Gambling (Two-Up) Act, which stipulates that two-up is only legal on Anzac Day (April 25th), Victory in the Pacific Day (August 15) and Remembrance Day (November 11, but only after 12 noon).
"The Gambling (Two-up) Act 1998 does not legalise the playing of two-up at any other time. The only exception to this is Broken Hill, where two-up is played all year round under a special licence from the NSW Government," says the NSW Department of Liquor and Gaming.
Broken Hill has special exemption because of its strong history with the game. It was so popular at one of the town's local cafes that it was only forced to stop running games in 1984.
In most other states, two-up must be played as part of a formal horse racing competition, or at a casino.
WATCH BELOW: The real story behind the Anzac biscuit. Story continues after video.
How do you play Two-Up?
Here's an easy step-by-step guide.
- A designated "spinner" tosses two coins into the air off a piece of wood called a "kip".
- Everyone playing stands in a circle, called "the ring", and places bets on whether the flipped coins will fall on both heads, both tails or one head and one tail.
- Find a friend or a stranger to bet against. Then make a bet by placing a note - either a $5, $10, $20, $50 or $100 if you're feeling flush - on your head or your bottom, depending on your choice.
- The coins are tossed into the air and if your bet was correct, you get to keep both your money AND the cash bet by your competitor.