spill the beans

(verb) to reveal a secret accidentally or on purpose

Example Sentences:

A: I’m pregnant.
B: Oh no! You’re only 15!
A: I know! You can’t tell anyone!
B: Don’t worry. I won’t spill the beans.

I spilled the beans about the surprise party, by telling the birthday girl. I feel so stupid!

Ted never tells Mary anything, because she’s always spilling the beans. Last week she told everyone that he’s getting a divorce!

Similar idioms:

1. a hill of beans