Resting smirk face

A condition where someone's neutral face is to look like they find everything highly amusing.

Marr: They say this proposal is a serious risk to manufacturing and industry, with huge costs...

Priti Patel, government minister: *Smirk*

Marr: I don't see why you're laughing.

- The Andrew Marr Show, BBC Television,

Viewer: She might well be a cold hearted ghoul, but that's just resting smirk face.