I've heard this idiom several times. But I can't find it in my dictionary.
Some forums in my country said it means "really" or it expresses surprise, and they give me an example:

-I make it!
-You don't say!
-Don't mock me! I‘ll beat him.

But it doesn't fit the context of the samples I've encountered.
For example:

A: Mr. Qian, what does he do exactly?
B: Gambling, man! What do you think?
A: Brother! You, me, and him, we're gonna work together.I tell you now. We're gonna work this out.
B: You don't say!

I feel it means "It's obvious. You don't need to tell me that."

Could someone be kind to tell me what exactly this idiom means?

3 Answers 3


It basically means exactly what you say that's super obvious or you don't need to even say that.

"The square root of 4 is 2"
"You don't say!"

Another one people often use to say the same thing would be calling someone captain obvious.

"The square root of 4 is 2"
"Thanks Captain Obvious!"

A site to read for a good definition of this: You don't say in the The Free Dictionary

Look at the second definition: 2.Inf. You have just said something that everybody already knows.

The first definition you might here though is the non-sarcastic one, which is a genuinely surprised response to something someone said.

  • 3
    I'd say rather it means what it means, which can be surprise or acknowledgement. But as with anything it can be used ironically, e.g. "You are so smart!" Every language has some degree of irony.
    – Andrew
    Commented Mar 13, 2018 at 17:38
  • In all fairness, I did include the two dictionary definitions of what it can mean. It's just so frequent to see it used ironically, I thought it should be included first, if that makes sense. I cannot personally think of a time in my (rather short) life so far where someone has used it outside of a sarcastic context, but I'm young;)
    – Element115
    Commented Mar 13, 2018 at 17:41
  • Do the kids nowadays still say "For realz?" or is that dated? All I know about current slang is what I hear in the movies and TV :)
    – Andrew
    Commented Mar 13, 2018 at 17:42
  • Haven't heard it in college, but certainly did hear it in high school:P "Bro, Tommy just kissed Lauren!" For realz bro?!":)
    – Element115
    Commented Mar 13, 2018 at 17:47
  • It's a genuine idiom—I (NNS, Russian) just can't make sense of it basing on the words it comprises. Is it an imperative or indicative phrase? The thing is aggravated by the fact that there is an identical phrase in Russian which means emphatic agreement + disapproval, something like "indeed": - Этот салат невозможно есть! (This salad is inedible!) - Не говори, меня чуть не стошнило! (Don't say, I nearly threw up!) Commented Mar 13, 2018 at 19:27

It's merely another saying of surprise or incredulity, not meant to be taken literally.

Similar phrases:

Well, I'll be [darned, damned, hornswoggled, etc.].
Well, what do you know about that?
Of course!

It can also be used sarcastically, as @Element115 notes, but that is not the principal meaning.


The Macmillan dictionary tells you the idiom “You don’t say” has contradictory meanings.

  1. used to express surprise.
  2. used to express lack of surprise.

This is because you can say “You don’t say that, do you?” (It’s not an imperative.) in the both situations. For one unbelievably surprising, and for another one that is so obvious that it’s needless to be said (i.e. saying it is unbelievable).

Maybe you can call it a contranym, just like the word “virtual.”

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