The SSSS info on a Boarding Pass means you've been pre-selected for additional security screening. The SSSS passenger is chosen randomly. 

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The barcode on any boarding pass gives access to all that passenger’s associated information, such as their name and flight details. But the barcode will also reveal one key piece of information: The passenger’s full airline account number. Sometimes, additional details belonging to the account, such as email address, phone number, and more, will also be available.