Idiom - Let the cat out of the bag

Let the cat out of the bag:

If you let the cat out of the bag, you let someone know a secret.

We'd planned a surprise party for Donna, but some guy she works with let the cat out of the bag, so now she knows.

Don't forget that this is a secret, so whatever you do, don't let the cat out of the bag.

Persian: لو دادن

Origin: Possibly related to the fact that in England in the Middle Ages, piglets were usually sold in bags at markets. Sometimes, someone would try to cheat a buyer by putting a cat in one of the bags instead of a piglet. And if someone let the cat out of the bag, the fraudster's secret was revealed.

Idiom - In the Bag

In the Bag:

(Slang) If you think something is "in the bag", you are sure you'll get it or achieve it.

If the polls are correct, the Democrats have the election in the bag. They should win easily.

They are three goals up with only five minutes to go, so Liverpool has got this game in the bag. They won't lose now.