The ‘SSSS’ on your boarding pass stands for “Secondary Security Screening Selection”, and it is every bit as fun as it sounds (read: not at all fun).

They are put through a more intensive screening process, which “may include enhanced pat-downs”.

According to a document on security processes leaked in 2009, it is also likely that “carry-on luggage may also be inspected by hand, [and], in the case of film or other items that cannot be X-rayed, the agent may perform a test for possible explosive materials.

“The screener may also use a handheld metal detector to search the passenger for metal objects.”

The truth about that ‘SSSS’ airport stamp on your boarding pass