say a mouthful
Fig. to say a lot; to say something very important or meaningful. When you said things were busy around here, you said a mouthful. It is terribly busy. You sure said a mouthful, Bob. Things are really busy.
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!