Letting the Cat out of the bag

This term comes from the old naval punishment of being whipped with a ‘cat o’ nine tails.’ The whip was kept in a leather bag and when the sailors ‘let the Cat out of the bag’ they had usually done something that would result in punishment. The term is used today to mean that someone has said something that was not to be said or revealed a secret. A nautical term that has now become part of everyday language