ㄌㄡˋㄔㄨㄇㄚˇㄐㄧㄠˇlòuchū‑mǎjiǎo

露出马脚
  1. 比喻無意中現出破綻 經過警方努力追查詐騙集團終於露出馬腳」。

to reveal the cloven foot (idiom)​; to unmask one's true nature, to give the game away