you're telling me
01
私に言うな！, 教えてくれるな！
used to show strong agreement with a statement, often implying the speaker already experienced or knew it
Slang
例
That traffic jam is brutal — you're telling me!
あの渋滞はひどい—言わなくてもわかってるよ！
Finals week is exhausting — you're telling me!
期末試験週は疲れる—言われなくても分かってるよ！
