A checklist, used by the TSA, leaked online last week.
It’s a list of 92 different reasons for giving someone a pat down.

Yup, It’s not a 6th sense that helps airport security keep the bad guys off airplanes after all. There is a check list of suspicious activities to look for, such as yawning, whistling, and complaining too much.
If you are flying anytime soon–and don’t want to accidentally look suspicous–check out the full list here