noun
feigned innocence; blank look
Describes a facial expression that pretends not to know something, often used when someone is playing dumb or acting innocent.
彼はとぼけ顔で「何のこと？」と言った。
He said 'What do you mean?' with a face of feigned innocence.
いたずらをした後、猫はとぼけ顔で座っていた。
After the mischief, the cat sat there with a blank look.
Compound of とぼけ (continuative form of とぼける 'to play dumb') + 顔 (かお 'face'). The exact origin of とぼける is uncertain, but it is a native Japanese verb.