The SSSS notation on your boarding pass is most certainly NOT random.
It is generated by the airlines' check-in process according to some out-dated and completely spurious logic (see: CAPPS).
There is so-called random additional screening (the pat-downs/wandings) at the checkpoint, determined by the screeners. Mostly it's not truly random either, more likely you did something to p!ss the screener(s) off.
Last edited by PaperTiger; 22nd May 2008 at 16:00.