u really beat me.

In some situation it means I admire you. Others mean I m speechless to you.

haha, it;s interesting, I wonder how do you get it, it is popular in Chinese. ok, it means you are shocked by something or behavior( always things are incredible or crazy), and you have nothing to say to retort but receive.

服了 situation: somone does something,and you admire of him = 服了 maybe： I 服了 U = You are right.

Generally I use it in a sarcastic way just like "Oh! Come on!" But I think it's not a hot word now.