you can say that again

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® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.