Saying ‘bomb’ in an airport

This is a big no-no. People get carted off to jail for saying bomb in an airport. But why?

Do terrorists talk about bombs while they're in the security line? "Hey Bob, you still have the bomb? You didn't leave it at Starbucks did you?".

Has there ever been a single case where acting on someone uttering the word 'bomb' in an airport has led to the discovery of an actual threat?