Spill the beans: to give away a secret or surprise; to let secret information become known
这个常用口语的意思是泄密，暴露真相。有的时候也可以说spill the works，意思是一样的。
造句：
a). There is a surprise party for Jessica on Saturday. Please don’t spill the beans.
b). He has been trying hard not to spill the beans about his secret purchases.