Let The Cat out of The Bag
Let The Cat out of The Bag : Phrases
To reveal a secret.
Don't let the cat out of the bag about Karla's birthday present.
At medieval markets, unscrupulous traders would display a pig for sale. However, the pig was always given to the customer in a bag, with strict instructions not to open the bag until they were some way away. The trader would hand the customer a bag containing something that wriggled, and it was only later that the buyer would find he'd been conned when he opened the bag to reveal that it contained a cat, not a pig. Therefore, letting the cat out of the bag revealed the secret of the con trick.
Alternative : At one time and even today in some circles, some people who have unwanted cats put them in a gunny sack with some large rocks and drop the whole thing in the river. Some people would find this practice objectionable - hence a desire to keep it a secret. Letting the cat out of the bag would divulge that secret.
Related Phrase : Buy A Pig in A Poke
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