She gasped and stared at him with her mouth open.

I stared at her with my mouth in the classic O sign.

When she finished, Foster was staring at her with his mouth open.

And he went back to staring at her with his mouth open.

I was bewildered and probably stared at her with my mouth wide open.

Van stared after him with his mouth starting to fall open.

Homer just stared at her with his mouth slightly open.

He stared at her momentarily with his mouth wide open.

Just goes on staring with her mouth open like she's thinking of screaming but forgot how.

He stared at her with his mouth open; bit it shut.