resting smug face
a person, who appears to naturally have or show excessive pride in his/her self(self approving face) when his/her face is expressionless, without meaning to.
Kelly just has a resting smug face, she is actually a really humble person.
Resting Smug Face
We've all heard of resting bitch face, and I think we all know what it means. We would like to recognize other resting faces: people who just can't help but look a certain way without even trying. Our first is resting smug face: someone who just looks smug unless they're trying to look another way, like angry or amused.
That guy is so cocky, he even has resting smug face.