- To reveal a secret, usually unintentionally or carelessly.
Explanation
Origin
- The most popular theory relates to medieval markets. A common scam was to sell a cat in a bag (poke) instead of a more valuable piglet (pig in a poke).
- If the buyer opened the bag prematurely, the cat would jump out, revealing the secret deception – thus, letting the cat out of the bag.
- Another theory involves the cat-o'-nine-tails whip used in the British Navy, kept in a bag; taking it out revealed the secret of impending punishment. The market theory aligns better with the revealing a secret meaning. Dates to the 18th century.
Synonyms & Related Expressions
Alternatives
Slang/Informal:
- Spill the beans
- Spill the tea (modern slang, esp. for gossip)
- Blab / Blabbermouth (noun for the person)
- Squeal (esp. informing authorities)
- Blow it / Blew the surprise
- Open your big mouth / Shoot your mouth off
Vulgar/Emphatic:
- Fucking blew the secret
- Couldn't keep their fucking mouth shut
Milder/Formal:
- Reveal
- Disclose
- Divulge
- Make known
- Inadvertently reveal
- Compromise confidentiality
Situational Appropriateness
- Informal to semi-formal. A very common and widely understood idiom.
Misunderstanding Warnings
- Very unlikely to be misunderstood due to its common usage. The literal meaning is clearly not intended in most contexts.
Examples
- It was supposed to be a surprise party, but someone let the cat out of the bag.
- Don't let the cat out of the bag about the new project details yet.
- He accidentally let the cat out of the bag when talking to the reporter.
Dialogue
Anna: I got Dave those concert tickets he wanted for his birthday! It's a surprise.
Ben: Oh, about that... I think Sarah might have accidentally mentioned it to him yesterday.
Anna: What? Sarah let the cat out of the bag?! I told her specifically not to say anything!
Ben: I know, I think it just slipped out.
Social Media Examples
- Tweet: Looks like the game developers accidentally let the cat out of the bag about the release date in their latest patch notes! Oops! #gaming #leak
- Facebook post: Trying SO hard not to let the cat out of the bag about my sister's engagement before she announces it! 🤐 #secrets #familynews
- Comment: Someone definitely let the cat out of the bag early on this product launch.
Response Patterns
- Annoyance/Disappointment: Oh no! Who did it? / I can't believe someone spoiled the secret!
- Inquiry: How did it happen? / Who spilled the beans?
- Resignation: Well, the cat's out of the bag now, so we might as well discuss it openly.
- Confirmation (if accused): Oops, sorry! I didn't mean to let the cat out of the bag.
Common Follow-up Questions/Actions
- Trying to find out who revealed the secret and how.
- Discussing the consequences of the secret being known.
- Adjusting plans now that the information is public.
Conversation Starter
- No. Refers to the act of revealing information previously established or understood as secret.
Intonation
- Key stress usually falls on CAT and BAG. Who LET the CAT out of the BAG?
- Often said with annoyance, surprise, or resignation.
Generation Differences
- Used and understood across all generations.
Regional Variations
- Common in all English-speaking regions.