You Don't Say is a meme used to reply to obvious or stupid comments.
Use
You Don't Say is used as a reply to idiotic comments or obvious situations. However, "You Don't Say" is not always said as the punchline. It is usually replaced with a witty comment, like in the example below.
Trivia
- The origin of "You Don't Say" came from the movie Vampire's Kiss. The scene of the movie with the face is in the video above.