Doya-gao (ドヤ顔) is a facial expression conveying a self-satisfied, cocky, or smug attitude. To enhance the comedy effect, one may use this expression on a character who is overly proud of something they failed at, or that they have no reason to be proud of.
Doya probably comes from Kansai Japanese "Dou ya?" meaning asking someone "How about that?" or "How well am I doing?". The phrase carries an inside meaning of "I looked cool just now, didn't I?"
