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general::
Phrase(s): You (really) said a mouthful.
Inf. Fig. You said exactly what needed to be said.; What you said was very meaningful and had great impact. • Bill: Did you hear what I said to her? Jane: Yes. You said a mouthful. Was she mad? • Bill: This is the worst food I have ever eaten. It is either stale, wilted, dry, or soggy! Tom: You said a mouthful!
McGrawhill's American Idioms And Phrasal Verbs