Also, you said it. I totally agree with what you said, as in What a relief that Brian didn't get hurt.--You can say that again! or This is a huge house.--You said it. [Colloquial; first half of 1900s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Company. All rights reserved.