suffix
-looking; with a ... expression; resembling ...
Colloquial suffix attached to nouns or the -masu stem of verbs. Describes a facial expression, appearance, or air that resembles the base word.
彼は得意顔でみんなに結果を見せた。
He showed everyone the results with a proud look on his face.
子供たちは不思議顔でその箱を見つめていた。
The children stared at the box with puzzled expressions.
彼女は泣き顔を隠そうとした。
She tried to hide her tearful face.