Each week of 2017 we present an English idiom.
“to let the cat out of the bag”: to give away a secret, usually by accident (die Katze aus dem Sack lassen)
Example 1: The mid-year bonus for all employees is supposed to be a secret, so don’t let the cat out of the bag, okay?
Example 2: The cat was (let) out of the bag when Jim’s colleague read his email while Jim was out sick. Now everyone knows we’re running into serious financial problems.