You will be arrested if you joke around in an airport. When asked if he had hazardous materials, a man said he had dynamite. He was arrested and charged with "falsely reporting a bomb at an airport." Dynamite isn't a bomb, last I heard. But anyway, asking people this question only makes sense if the questioner can tell if the responder is lying. How likely is that?
In this airport situation, I am certain that there is tension, impatience, and a desire to express some freedom from the restraint and impositions of it all. I am certain that exactly what this man said out loud must have crossed the minds of many travellers: "Sure, I'm carrying an atom bomb, and I'm stupid enough to tell you, fool." He had the misfortune of not controlling his impulse and blurting it out. There is not free speech in an airport.