Comprehensive resource for understanding and mastering English idioms
"You can say that again" is an idiomatic expression used to indicate agreement or confirmation of what someone has just said. It expresses the idea that what someone has said is true or accurate, and that it was something that could be repeated without question.
This idiom can be used in a variety of contexts, such as when someone has made an observation that you agree with or when they have made a complaint that you understand and sympathize with. It can also be used to express surprise or astonishment at something that someone has said or done, especially if you didn't expect it.
The origin of this idiom is uncertain, but there are a few theories. One theory suggests that it comes from the phrase "it's true enough to be repeated," which would indicate that something was accurate or reliable and could be repeated without question. Another theory suggests that it comes from the phrase "that's what they said" or "that's what he said," both of which were common expressions used in the past to express agreement or confirmation with what someone else had said.