Spill the beans
Definition 1 of 1
Pro Tip 1/3Casual Expression
Used in informal settings among friends or family, not suitable for formal situations. 
At the family reunion, Joe couldn't wait and spilled the beans about his engagement.
Pro Tip 2/3Unexpected Reveal
Often implies a revelation that is surprising to others, like sharing a secret without prior planning. 
In the middle of the dinner, Clara spilled the beans about her brother's secret job.
Pro Tip 3/3Maintain Secrecy
Indicates the importance of keeping certain information confidential until a specific moment. 
The team was warned not to spill the beans about the new product before the launch date.