One of the most annoying aspects of airline travel are the endless security checks you're forced to undergo.
Some people have an interesting theory, and it goes like this. If you want to know if your time at the airport is going to be longer than usual, all you have to do it look down at your boarding pass to see if it is branded with this particular stamp:
"SSSS" stands for Secondary Security Screening Selection and a lot of British passengers are complaining about receiving the stamp multiple times while heading to the US.
There isn't much public information available to how the TSA qualifies someone as "SSSS," but if you've seen the code pop up on your boarding pass more than a couple of times, you can contact the TSA and appeal their decision to have you placed on the list.
Passengers who are familiar with the extra screening times revealed just how frustrating the entire process can be.
Seriously though the worst part about SSSS is that you have to do it at each connecting airport too. 👎— Jonathan Khoo (@jonk) August 5, 2017
People have also reported that receiving an "SSSS" boarding pass typically prevents you from accessing them from your phone. You'll need to print them from a kiosk at the airport or get them from an agent.
Of course, many people would argue that the extra security measures are worth the inconvenience, because safety comes first.