30-something years ago, when I first worked at Heathrow, there were words that the staff were banned from using over the PA system due to the possibility of spreading panic - "emergency", "urgently", "hurry" etc.

It was at the height of the IRA mainland bombing campaign, so there was many a time the terminals had to be evacuated in a calm and dignified manner whilst bombs, occasionally real and more frequently hoax, were dealt with.

Joking around with security men or airline staff about guns, bombs etc is not a good idea. Most of us lost friends, relatives or people that we had rubbed shoulders with on 09/11 - especially at British Airways. (Almost 40% of our regular Concorde clientele lost their lives in the twin towers on 09/11, so we're told, which is one reason why Concorde's continued service was considered unsustainable.) Certainly, anyone who worked in the industry on 09/11 will never, ever allow a passenger to joke about guns, bombs, knives etc.