ain't that the truth

expression Used to emphasize that one believes what someone else just said to be true. ("Ain't" is a colloquial contraction of "is not.") A: "As I get older, I start to value more and more the simplicity of reading a good book at home instead of going out to parties." B: "Ain't that the truth!" A: "If you never travel, you'll always have a narrow worldview." B: "Ain't that the truth. It wasn't until I started visiting other countries that I began to understand the values and perspectives of other cultures." A: "Having grandkids really keeps you young." B: "Ain't that the truth."