don't say it
I know what you're about to say, and I don't want to hear it. I know I look bad, so don't say it. The kids kept me up half the night!
Don't say it!
I don 't want to hear it!; I know, so you don't have to say it. John (joking): What is that huge pile of stuff on your head? Bill:Don't say it! I know I need a haircut.