With that definition, I’d call it a guilty face or someone showing a guilty conscience.
I searched it for some more examples, and with the ones here and here, I’d call those examples someone having a solemn face (literal) or wearing a long face (idiomatic).
I remember us talking before about your local expressions. It’s all so interesting! In our area, some of us like myself get picked on sometimes for having Pennsylvania Dutch / Amish words or pronunciations.
With that definition, I’d call it a guilty face or someone showing a guilty conscience.
I searched it for some more examples, and with the ones here and here, I’d call those examples someone having a solemn face (literal) or wearing a long face (idiomatic).
I remember us talking before about your local expressions. It’s all so interesting! In our area, some of us like myself get picked on sometimes for having Pennsylvania Dutch / Amish words or pronunciations.