The term "The Cats Out Of The Bag" or "Letting The Cat Out Of The Bag" also comes from olden days, ships at sea, the British Navy Captains used to dole out punishment for infractions of the rules at sea. Common was receiving 'lashes' (being whipped). They would whip your back with a Cat-o-Nine Tails, which was a whip with nine tail ends on it. The whip or 'Cat' was kept in bag when not in use. When someone was getting punishment, the sailors would pass the word to one another by saying "The Cats Out Of The Bag". I believe you'll see this sort of punishment in movies like Munity on the Bounty, but don't recall if you'll hear the remark. Also, the worst type of punishment you could receive was called 'Keel Hauling" where they tied a rope around your feet and the rope went all the way under the ship with the other end tied around your arms. They'd throw you over the side and haul you under the boat, around the 'Keel' or very bottom spine of the ship and then up the other side. Invariably, most men drowned from this punishment.