Since 9/11 I have been "Randomly Selected." About once a year that I have flown.
I've been patted down several times at the airport and have had to stand in that puffer machine that blows air checking for traces of explosives.
On one flight, there was a businessman that made a comment to a teenager that was pulled aside. He said "son, why do you have your shoes off?" and laughed. The TSA pulled him out of line immediately and made him go through the extra security as well.
He wasn't laughing anymore.