THE insanely popular In-N-Out Burger pop-up in Sydney today sold out of burgers half an hour before the store even opened.

How on earth did that happen, you ask?

Obsessive burger lovers were lining up outside Dead Ringer restaurant in Surry Hills since 6am, desperate to get their hands on a burger.

While the pop-up store didn’t open until noon, staff were handing out wristbands to people in the queue and implemented a one-burger-per-person policy. They ran out of wristbands at 11.30am.

People have been lining up for #InNOutBurger Sydney since 6am. Look at that line: pic.twitter.com/9POM3QH7ui — Time Out Sydney (@SydneyTimeOut) January 20, 2016

Since its inception in 1948, In-N-Out has gained a cult following all over the world for its simple but tasty burgers. Based out of Irvine, near Los Angeles, In-N-Out outlets can be found all over California. It’s also expanded to outlets in Arizona, Nevada, Utah and Oregon.

It has a pared back menu with three burgers on offer: the basic hamburger, a cheeseburger and the Double-Double (double meat, double cheese). Add some fries (cheese optional) and shakes, and you’ve got a classic burger chain.

In-N-Out gained its hallowed reputation in part because it made its burgers fresh, cooked-to-order, rather than sitting behind the cashier for god knows how long. It’s also cheap — the basic hamburger is just over $US2 and you could get a whole meal for about $US5.

And while not quite as extreme as a four-hour window once every few years in Sydney, the fact that In-N-Out is only available on the West Coast of the US has lent it an air of exclusivity. As most visitors to California will know someone, somewhere, will tell you to get an In-N-Out burger while you’re in town.

The quick sellout in Sydney made things awkward for several Airtasker users who had agreed to line up, buy and deliver several burgers to desperate, but lazy, fans. Some were offering up to $60 for the task.

Sneha Rao accepted a $25 Airtasker request for five burgers, but missed out on a wrist band.

“I got there at 10am and there was already a queue around the block. The people in front of me had been waiting since 8.30am,” Miss Rao told news.com.au.

“They started handing out the wristbands at 11.15am and I missed out by five people. They said I could try next time but I needed to get there much earlier.

“I’m terribly disappointed. I just left the queue. People are crazy.”

Those lucky enough to get their hands on a wristband would have them wrapped around one of these burger choices — the Double-Double for $5, a cheeseburger for $4 or a hamburger for $3. Chips are only a dollar. You can even pick up a souvenir T-shirt for $4.

This isn’t the first time the restaurant has come Down Under — previous pop-ups at Darlinghurst eatery Love Tilly Devine and Parramatta Mixology Lounge have also seen huge queues and a quick sellout.

Dead Ringer said it doesn’t have any other plans with In-N-Out, and it’s unclear if the US burger chain has any other pop-ups slated for Australia.

People are still showing up to line up at the Sydney In-N-Out pop up. It's sold out, guys. pic.twitter.com/lV8ahap8ZM — Johnny Lieu (@Johnny_Lieu) January 20, 2016

Of course, if you’re baulking at the thought of lining up for hours for a burger, don’t forget about the glorious Aussie joints that dominate Instagram on any other day.

Huxtaburger in Melbourne is extremely popular, along with Mary’s in Sydney, Jack Greene in Hobart, Brodburger in Canberra, Bilby’s in Perth, Burger Lounge in Coolangatta, and your local milk bar, who probably still do a mean burger with the lot.

Some burger aficionados will tell you that there are American burgers that beat what In-N-Out has on offer.

SHAKE SHACK

It’s been said that you can tell if an American is an East Coaster or a West Coaster by how they answer this question: In-N-Out or Shake Shack?

If you’re a West Coaster, it’s hands-down In-N-Out, and if you’re from the East, then it’s Shake Shack by a mile.

Founded in Manhattan’s Madison Square Park in 2004, Shake Shake has spread across the East Coast with locations across New York, Boston, Washington DC, Pennsylvania, Florida and more. It’s even expanded to Dubai and Turkey, Russia and Japan.

When burger shop Jack’s opened in Newtown, Sydney at the end of last year, it sold out every day because news articles likened its burgers to Shake Shack.

Oh yeah, it’s also got really good frozen custard shakes.

BURGER JOINT

Tucked away behind hoarding in the lobby of Manhattan’s Le Parker Meridien Hotel in Midtown, Burger Joint is a jumping eatery where the line reaches to the lobby by just after midday.

Line up at the cashier and you better have the answer to the most important question ready: How do you want it cooked? If you answer something other than medium-rare, be prepared for a withering look.

You can also grab a jug of beer or a glass of red wine to throw back with your burger.

Burger Joint recently opened an outlet in Singapore.

Did you manage to get your hands on an In-N-Out Burger today? Tweet us a photo at @newscomauhq, @beck_sullivan or email rebecca.sullivan@news.com.au