let the cat out of the bag
accidentally reveal a secret
In Spanish
irse de la lengua
Examples
- Don't let the cat out of the bag about the new product.
- She let the cat out of the bag about the surprise party.
- During the interview, he let the cat out of the bag about his new project.
When it's used
This idiom is informal and often used in everyday conversation. It is suitable for situations where someone accidentally reveals a secret. It is not typically used in formal writing or speech.
The common mistake
A common mistake is using the literal calque 'go from the tongue', which is not English. English speakers would not understand this to mean revealing a secret.