Definition
Used to express surprise or, in a humorous and slightly sarcastic way, to express a lack of surprise.
（表示惊讶或不惊讶）真的吗！
"I heard they're getting married." "You don't say!"
「我听说他们要结婚了。」「真的吗！」
"She's late again." "You don't say!"
「她又迟到了。」「真的吗！」
"He failed the exam!" "You don't say!"
「他考试不及格！」「真的吗！」