My mouth dropped open for a second, but I said nothing.

Her mouth sort of dropped open when she saw me.

His mouth dropped as if she'd hit him with a board.

When he saw what was inside, his mouth dropped open.

Then, he got a good look at the boy, and his mouth dropped open.

All eyes turned and almost immediately every man's mouth dropped open.

Instead, her mouth dropped open as she read the name of the judge sitting on the case.

His mouth dropped open at what he saw directly below.

His mouth dropped open as she shut the door behind her.

His mouth dropped open to speak, but he closed it without saying a word.