True story I witnessed. It was in San Francisco International Airport May 2002. I was behind a woman and a little boy, waiting to check in. Bear in mind, we are operating under super paranoia at the time. Back then, it was a required practice for the check in staff to ask question regarding are you carrying any prohibited items, explosive, guns etc etc with you. I agree, it's stupid questions, but i was asked those questions hundreds of times.
Well, this woman, by now, agitated, for what I have no idea, but answered the question by saying, something like... if I were carrying these items, will I tell you, what stupid questions are these. I remember the "stupid" commets. The check in agent continued to process her check in, but I observed, she was stalling. Within minutes, 3 guys and 1 woman in dark suit showed up, the woman and her kid was escorted away.
No scene, no comotion, but we standing behind had a good laugh.