Every Guinness drinker knows that there's a 'right' way to pour Guinness.
Branded glass, 45-degree tilted pour, wait, top up, and serve.
This is the key bit — letting the beer "Surge." It's often called settling.
It's the annoying part, when the beer's 3/4 full and the bartender puts it down to finish the rest of the round, or even take someone else's order. All the while, your beer sits there apparently doing nothing. But everyone who's ever had a Guinness or poured one has been told how important this is.
There's even an exact time for it, which is 1 minute and 32.5 seconds.
SHOCKER... It is completely unnecessary to leave the Guinness to settle. Always. It has no impact on the flavour.
During the 1950s, Guinness replaced their traditional wooden casks with nitrogen-charged metal casks, but customers were unconvinced.
The two-pour method had briefly been necessary during the decade-long changeover from wooden to metal casks.
Some drinkers maintain that the two-pour is still necessary to produce the thick, 'domed' head as below.
It's also possible that drinkers are so used to the process, they actually find the drink tastes better.
In which case, carry on. Though you will need to wait longer at the bar.
Guinness themselves stick rigidly to the official process, producing literature and working with bars and lifestyle publications to ensure the "proper" method of pouring Guinness is very widely known.
The unique pouring method was then heavily integrated into some admittedly brilliant marketing campaigns as a unique quality of the drink.
It's very easy to see the influence of the myth. The 1 minute 32.5 second alleged "settle" time is actually the length of every advert that Guinness produce.
10 million pints of Guinness are drunk every day. That means that the equivalent of 29 YEARS is spent waiting for Guinness across the globe, every single day.
Still, it's delicious, so maybe just enjoy your pint regardless of how it's poured.
Though anyone putting a shamrock in the foam should still be banned from ever pouring another pint. In Belfast, this is known as "piss in the pint."