Being selected for "SSSS" (Secondary Security Screening Selection) on a boarding pass typically happens for one of three reasons: random selection, specific travel patterns, or being on a government watch list. The Transportation Security Administration (TSA) uses a confidential algorithm to flag passengers who might require extra scrutiny. Triggers often include booking a one-way international ticket, paying for a flight in cash, purchasing a ticket at the very last minute, or having a travel history that includes countries considered high-risk by the Department of Homeland Security. Sometimes, a "name mismatch"—where your name is similar to someone on a security list—can cause repeated selections. If you find SSSS on your pass, you will likely be unable to check in online or at a kiosk and must see an agent. At the security checkpoint, you will undergo a more intensive screening process, which often includes a full-body pat-down, a thorough search of all carry-on bags, and a swab of your hands and electronic devices to test for explosive residue. While inconvenient, it is a standard security protocol designed to add an unpredictable layer of safety to the aviation system.