馬脚 ばきゃく あらわ
bakyakuo arawasu

Godan Verb (su)
Idiomatic Expression

1. to reveal one's true nature; to show one's true colours; to give oneself away; to be exposed (of a lie, etc.)

かれもついに馬脚 ばきゃく あらわした。
karemo tsuini bakyakuo arawa shita.
He has finally shown his true colors.
Other forms: