In LAX the screeners confiscated a one and a half inch toy pistol on my son's keyring. I protested until the guy explained that there ARE weapons that small and demonstrated how it could be used to threaten cabin staff. I threw it in the bin.
I was in Honolulu last year and warned a first time Canadian passenger to turn off his video camera in the customs hall with the usual response of getting told to f&*^ off. He was very very lucky to get away with a tongue lashing by an extremly large and voluble U.S. Customs lady and the surrender of his holiday video tape.
Some people learn, some people don't