Idiots, indeed.
There was a man in Columbus, OH 09/11 that was in the state office tower(41 floors, 4K people) to install window blinds for an outside company. Being unknown to staff in the building, I guess quite a few different people asked who he was. He allegedly told one of the staff that he was there to "hide the bomb".
One staff member contacted authorites while another confronted him. The man appologised and admitted that was he said wasn't appropriate or funny. Authorities arrived and questioned him, and a bomb sniffing dog arrived and alerted to a "hit" on his truck. (The "hit" turned out later to be a propellant for a nail gun). The entire building was evacuated.
The man is being held and charged with inducing panic. It was also learned that he is an illegal immigrant that overstayed his visa about 3 years ago. INS is considering shipping him and his 3 kids back to Mexico.