It is essential that we retain our sense of humour and make sure our airports are safe for passengers without overkill reactions by those in charge of them.
Making a joke is not an offence but beware, it can turn into one, as reported by Alex Murray about Gatwick Airport (The Mail P28 July 16, 2010, quoted from The Spectator). He was tricked into mentioning the word three times and then five armed police were called, all armed with submachine guns and anti-terrorist equipment. Both he and his wife were questioned by the police in separate rooms, not allowed to fly and forced to leave the airport. Please remove this stupid rule and make sure airport staff are trained not to play tricks on passengers.