Don't let the cat out of the bag意思

"Don't let the cat out of the bag" is an English idiom that means to not reveal a secret or important piece of information that is meant to be kept hidden or confidential. The phrase is often used as a warning or reminder to someone to keep quiet about something they might accidentally or inadvertently reveal.

The origin of this idiom is not definitively known, but there are a few theories. One theory suggests that it comes from the practice in the 19th century of selling pigs in markets, where a cat would sometimes be substituted for a piglet in a bag, and the buyer would get the "cat out of the bag" when they discovered they had been tricked. Another theory is that it may have originated from the practice of using cats to catch rats on ships, and the phrase was used to mean "don't reveal the secret of the ship's cat."

Regardless of its origin, the phrase has been in use for several centuries and is still commonly used in both British and American English.