Open your mouth wide and say "Ah."
You shouldn't put so much food in your mouth at once.
[The doll] is my fav[or]ite birthday present, because it has two big eyes, a small nose and a small mouth. (Key English Test; A2; Chinese)
He told me to keep my mouth shut.
She made every effort to keep her mouth shut but it disturbed her to be the only one to know the truth, apart from her brother. (First Certificate in English; B2; Turkish)
Just shut your mouth and stop whining!
But I couldn't shut my mouth, I continued: "You can't believe it Pat, she wears trousers like men and green flowery blouses." (First Certificate in English; B2; Spanish)
It is a small village, by the mouth of a river.
The mouth of the river with a [narrow] exit to the sea, provided an extra ex[c]itement because of the pressure of the water when joining the sea. (Certificate of Proficiency in English; C2; Portuguese)
Students learned of the center by word of mouth.
In the past news traveled mostly by word of mouth and it took days and sometimes weeks before a person would become aware of an occurrence on the other end of the world. (International English Language Testing System; C2; English)
He makes outrageous comments and is always putting his foot in his mouth.