1
general::
Phrase(s): You don’t say.
1. Inf. a general response to something that someone has said. (Expresses a little polite surprise or interest, but not disbelief.) • Bill: I’m starting work on a new job next Monday. Bob: You don’t say. • Sally: The Jones boys are keeping a pet snake. Alice: You don’t say. 2. Inf. You have just said something that everybody already knows. • Bill: I think I’m beginning to put on a little weight. Jane: You don’t say. • John: My goodness, prices are getting high. Sue: You don’t say.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
How surprising, is that true? Also, I find that hard to believe. For example, I've been working on this project for two years.?? You don't say, or The man who runs this soup kitchen is a real saint.You don't say! This expression, a shortening of you don't say so, may be used straightforwardly or ironically. [Late 1800s]
American Heritage Idioms