Originally Posted by
NoLaGent
Secondary Security Screening Selection or Secondary Security Screening Selectee, known by its acronym SSSS, is an airport security measure in the United States which randomly selects passengers for additional inspection.
OK, I was unfamiliar with the acronym. I've had that happen in the past where during TSA screening they've pulled me aside and checked my hands for explosive material - a random event. But that did not prevent me from checking in the day before and I don't see why SSSS would prevent checking in anyway.