DAILY UPDATED IDIOM WITH PICTURES. LET THE CAT OUT OF THE BAG.

englishonline.org.cn
PRONUNCIATION. http://www.englishonline.org.cn/en/listen-watch/language-snacks/cat

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

For example:

• 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.

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.
goenglish.com

Quick Quiz:

After Julie let the cat out of the bag,

everybody laughed we all knew they ran after it ENGLISHCLUB.COM

Click for answer b.