shake your head
shake (one's) head
1. Literally, to rotate one's head back and forth (to the left and to the right) to indicate a negative response, disagreement, or disapproval. When I asked the little girl if she knew where her mommy was, she just shook her head. I see you back there shaking your head no. Is there something you disagree with?
2. To express confusion or bewilderment about something that has just happened or been revealed. This usage does not always indicate a literal movement of the head. When he abruptly exited the meeting without explanation, we all just sat there shaking our heads. Just shaking my head right now. What was that all about?