People only just realising what secret code ‘SSSS’ means and why you really don’t want to see it on your boarding pass

I think we can all agree that going to the airport can be a stressful affair, whether it's fumbling with your liquids and stuffing them in that tiny clear bag, or the sheer tension as you wait to see if the bag you had to sit on to zip up is, in fact, overweight.

But if you spot this 'secret' four-letter code on your boarding pass on top of all that, it could add a whole other layer of stress to your airport run.

And it'll spell bad news for all the airport dads out there who like to have their trip to the airport timed down to the minute, as it could mean you're going to be held back a bit longer at security.

The code - which has been reassuringly branded as the 'kiss of death - reads as 'SSSS' and can typically be spotted in the bottom corner of your boarding pass.

Airports can be stressful places (Hinterhaus Productions/Getty stock photo)

For anyone suddenly panicking as they plan a trip to Benidorm with the girls or a chilled week in the south of France, don't worry, as the code only affects those travelling to and from the US.

What does it mean if you see 'SSSS' on your boarding pass?

In short, SSSS stands for 'Secondary Security Screening Selection', which means that those unlucky enough to be slapped with the code on their boarding pass could be spending a little while longer at security.

It affects those on both domestic and international flights to and from the US, and can see travellers subjected to added security protocols such as bag searches and extra body pat downs or scans.

The time you're potentially delayed for could be anything from a few minutes to an hour, explains Travel and Leisure, as the checks themselves can differ from flyer to flyer.

Talking to Fox News, senior aviation writer for The Point Guys, Zach Griff, explained: "Selectees for this enhanced security are chosen in the days leading up to a flight when airlines share the manifest with US security authorities.

You could end up spending a bit longer here (Chalabala/Getty stock photo)

“SSSS can also be entirely random, and there’s no way to know when booking your flight whether you’ll be chosen as SSSS."

While it might be annoying to be held up for any length of time, the Transportation Security Administration (TSA) stressed that it's a highly necessary security measure designed to keep everyone safe.

A TSA spokesperson told Fox News: "Security measures begin long before passengers arrive at the airport.

"TSA works closely with the intelligence and law enforcement communities to share information."

It added: "Additional security measures are in place from the time passengers get to the airport until they arrive at their destination.

"In some cases, passengers are randomly selected for enhanced screening.”

Don't even think about trying to refuse any additional checks either, as the TSA warned no one is able to bypass the screening.

So, if you spot the dreaded four letters on your boarding pass, be prepared to take a little longer in that security line - and probably be gasping for that airport pint after.