BE YOUR SELF!!

let the cat out of the bag意為
 (informal English) to tell a secret, esp. unintentionally
(非正式英文) 洩露秘密 (尤其是指無意中洩露秘密)
 to let the cat out of the bag was to expose the fraud 揭發內幕
 New York Times let the cat out of the bag in the FedEx case.

這個比較對
let the cat out of the bag對應的是
sell a pig in a poke.(掛羊頭賣狗肉)

這原來是西方農村市集的一個慣用騙局
小販隨便抓隻貓放布袋裡, 假裝豬仔賣人
(sell a pig in a poke)
成交了還騙農民說豬仔怕見光, 會養不大
要回到農莊後才能開布袋
回去一開布袋, 騙局就曝光了
(let the cat out of the bag)