To “let the cat out of the bag” is a colloquial phrase that means to tell some facts that were perhaps a secret beforehand. It can be positive or negative information, and it can be used whether or not you accidentally told the information, or did it on purpose.
Origin Of The Phrase “Let The Cat Out Of The Bag”
There are a few theories as to the origins of the phrase “let the cat out of the bag.” The first is that, in the middle ages, sellers would swindle customers by placing a cat in a bag instead of a pig. When the buyer got home, they would let the cat out, and see they had been tricked. However, this theory doesn’t hold much weight. There would be a big weight difference between a cat and a pig, and getting a cat, or a pig for that matter, into a bag might not be an easy task depending on the temperament of the animal.
Another theory is that the word cat refers to a type of whip used in nautical punishments called a cat-o-nine tails. This whip was kept in a red bag, and it may have been said that the sailor who revealed the crime of another was “letting the cat out of the bag.”
The most likely theory is that if you imagine it, it would simply be impossible to get a cat back into a bag once you let it out, much in the same way that it is impossible to put a secret back once it is let out.
The first published written usage of this phrase was in 1760. It appeared in a book review in the London Magazine. However, it was also used in a letter from Johannes Agricola to Martin Luther during the Protestant Reformation in 1530.

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Examples Of Everday Usage Of The Phrase “Let The Cat Out Of The Bag”
You can use this phrase to refer to any secret that you divulge, whether it is a positive or negative secret or something you meant to tell or told by accident. It can be used in pretty much any context where there is a secret involved, whether it is business, family, friendships, or something else entirely. Once the secret is out, there’s no putting it back!
A Useful Way To Illustrate The Phrase “Let The Cat Out Of The Bag”
This is a fictional story to show a great example of the use of this phrase.
Imagine that you have a friend who is pregnant. She told you but she didn’t want to tell anyone else just yet. You are at a party and you forgot that the pregnancy was a secret. You are talking to your pregnant friend and she is talking about her vacation schedule. “In June, we are going to England!” She exclaims. Then you say “And, then you’re having the baby in September right?” Everyone at the party turns around and gasps. The cat is out of the bag! Now everyone knows that your friend is pregnant.

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A Real-Life Example From Forbes
In May of 2022, an article on the Forbes website described how President Biden said that higher gas prices were a necessary part of shifting to alternative energy sources like solar and wind. The author of the article, Steve Forbes, said that this “confession” was Biden letting the cat out of the bag in regard to this energy industry secret, before going on to explain his thoughts on the matter.
Possible Pros And Cons Of Using The Phrase “Let The Cat Out Of The Bag”
This phrase isn’t really offensive to use on someone who has let out a secret. However, it could be used in a moment of frustration if someone let out a secret that they shouldn’t have. In general, there’s nothing wrong with using this phrase to describe a secret getting out, whether or not you meant for it to come out.

©iStock.com/Denis Valakhanovich
Similar Phrases To “Let The Cat Out Of The Bag”
There are a few idioms in the English language that have a similar meaning to “let the cat out of the bag.” However, these phrases don’t have exactly the same meaning, so make sure you understand the meaning before you use them!
- Spill the beans
- Give the game away
- Blow the gaff
- Blow the lid off
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FAQs (Frequently Asked Questions)
What does the phrase “let the cat out of the bag” mean?
To “let the cat out of the bag” means to tell some facts that were perhaps a secret beforehand.
What are the origins of the phrase “let the cat out of the bag”
One origin theory of the phrase “let the cat out of the bag” comes from the middle ages. Sellers would swindle customers by placing a cat in a bag instead of a pig. When the buyer got home, they would let the cat out, and see they had been tricked.
Another theory is that the word cat refers to a type of whip used in nautical punishments called a cat-o-nine tails. This whip was kept in a red bag, and it may have been said that the sailor who revealed the crime of another was “letting the cat out of the bag.”
The most likely theory is that if you imagine it, it would simply be impossible to get a cat back into a bag once you let it out, much in the same way that it is impossible to put a secret back once it is let out.
What was the first written usage of the phrase “let the cat out of the bag”?
The first published written usage of this phrase was in 1760. It appeared in a book review in the London Magazine. However, it was also used in a letter from Johannes Agricola to Martin Luther during the Protestant Reformation in 1530.
What are phrases with a similar meaning to “let the cat out of the bag”?
Similar phrases to “let the cat out of the bag” include:
- Spill the beans
- Give the game away
- Blow the gaff
- Blow the lid off

I am broadly interested in how human activities influence the ability of wildlife to persist in the modified environments that we create.
Specifically, my research investigates how the configuration and composition of landscapes influence the movement and population dynamics of forest birds. Both natural and human-derived fragmenting of habitat can influence where birds settle, how they access the resources they need to survive and reproduce, and these factors in turn affect population demographics. Most recently, I have been studying the ability of individuals to move through and utilize forested areas which have been modified through timber harvest as they seek out resources for the breeding and postfledging phases. As well I am working in collaboration with Parks Canada scientists to examine in the influence of high density moose populations on forest bird communities in Gros Morne National Park. Many of my projects are conducted in collaboration or consultation with representatives of industry and government agencies, seeking to improve the management and sustainability of natural resource extraction.