这句话在什么语境中用“You\'re telling me”

"我早就知道啦！”的意思。
用在当别人和你说一件你很清楚的事情的时候，你就可以这么说拉！

E.G.：
Flevy: How often do you brush your teeth?
Jacky: After every meal. I want to keep them healthy.
Flevy: Me too. But do you floss? My dentist says that's very important, too!
Jacky: You're telling me! I have been flossing my whole life!

"It's raining outside." "You're telling me-I've been out to get the paper and I'm absolutely soaked.":

"外面在下雨。""我早就知道了--刚才我出去取报纸淋了个透湿。"

用于同意别人的意见时,相当于,you said it / i agree with you