To spill the beans is to reveal a secret unintentionally. This informal idiom is very common in American English. This expression has been in use since early twentieth century.
- I didn’t want anyone to know about my engagement to Susie, but my sister spilled the beans. (= My sister unintentionally revealed the secret.)
- When he refused to marry her, she threatened to spill the beans about their affair with his wife.
- I want the party to be a secret. Please don’t spill the beans.
The idiom let the cat out of the bag has a similar meaning.
What does the following sentence mean?
He didn’t want his parents to find out that he was in a relationship with his colleague, but his roommate spilled the beans.
- His roommate intentionally told his parents that he was in a relationship with his colleague.
- His roommate unintentionally revealed that he was in a relationship with his colleague
- His roommate didn’t reveal any secret.