give a blank look
give (someone) a blank look
To look at someone with a facial expression with no emotional articulation, usually implying befuddlement, incomprehension, or being overwhelmed by something. I tried to explain to him why what he did was wrong, but he just sat there, giving me a blank look. Claire just gives me a blank look any time I ask her about that traumatic accident.
give someone a blank lookand give someone a blank stare
to look back at someone with a neutral look on one's face. After I told her to stop smoking, she just gave me a blank look and kept puffing.