History lesson: It was the law in the ancient city of Amyclae to hold ones tongue, the Amyclaeans had often panicked when they hear rumours that the powerful spartan army was coming, so to put an end to defeatism, a law was passed forbidding rumours. Violators were to be executed. When the spartans did appear, no one had the courage to report it…the city was overcome without a fight.
Well not a good one anyway.
Now your starter for 10: Can you think of any modern parallel?