say a mouthful
To say something of great importance or meaning; say more by a sentence than the words usually mean. Usually in past tense.
Tom said a mouthful when he guessed that company was coming to visit. A dozen people came.
To vent one's honest opinion, even in anger.
He sure said a mouthful when he told his boss what was wrong with our business.
shoot off one's mouth
shoot off one's face
To give opinions without knowing all the facts; talk as if you know everything.
Tom has never been to Florida, but he's always shooting his mouth off about how superior Florida is to California.
I want to study the problem before I shoot off my face.
The editor of the newspaper is always shooting his mouth off about the trouble in Africa.
straight from the horse's mouth
Directly from the person or place where it began; from a reliable source or a person that cannot be doubted.
They are going to be married. I got the news straight from the horse's mouth - their minister.
John found out about the painting straight from the horse's mouth, from the painter himself.
take the bit in one's mouth
take the bit in one's teeth
To have your own way; take charge of things; take control of something.
When Mary wanted something, she was likely to take the bit in her teeth and her parents could do nothing with her.
take the bread out of one's mouth
To take away or not give your rightful support, especially through selfish pleasure.
She accused her husband of drinking and gambling - taking bread out of his children's mouths.
take the words out of one's mouth
To say what another is just going to say; to put another's thought into words.
"Let's go to the beach tomorrow." "You took the words right out of my mouth; I was thinking of that."
I was going to suggest a movie, but she took the words out of my mouth and said she would like to see one.