let the cat out of the bag

US /lɛt ðə kæt aʊt əv ðə bæɡ/
UK /lɛt ðə kæt aʊt əv ðə bæɡ/
"let the cat out of the bag" picture
1.

泄露秘密, 说漏嘴

to reveal a secret, often accidentally

:
We were planning a surprise party for him, but his sister let the cat out of the bag.
我们正在为他策划一个惊喜派对,但他妹妹泄露了秘密
I accidentally let the cat out of the bag about their engagement.
我不小心泄露了他们订婚的秘密。