Default face

The look on somebody's face when they're just sitting there thinking or are doing nothing & have no other emotions. The a way a person's face naturally falls.

Everybody kept asking me if I was sad today! But, nobody understands that it's just my default face. I've just been zoned out lately.

Dude: Hey, is Shauna pissed off?
Dude 2: Nah, dude, that's just her default face.