Значение идиомы say a mouthful
[say a mouthful] 1. {v. phr.}, {slang} To say something of greatimportance or meaning; say more by a sentence than the words usuallymean. – Usually in past tense.
Tom said a mouthful when he guessedthat company was coming to visit. A dozen people came.
2. {v. phr.},{informal} To vent one’s honest opinion, even in anger.
He suresaid a mouthful when he told his boss what was wrong with ourbusiness.
Contrast: GET AN EARFUL.