露尾巴

lòuwěiba ㄌㄡˋ ㄨㄟˇ ˙ㄅㄚ

    • to let a flaw or secret slip out
    • to give oneself away

Character by character

Saying俗语俗語

Idiom惯用语 · Widely known

Literally
show the tail
Meaning
To let a flaw or secret slip out and be detected.

Sources