No Shit Sherlock! 废话！
You can reply with this when someone says something extremely obvious.
Person 1: *insert something stupid shit here*
Person 2: No Shit Sherlock!

Greasing 胡扯的艺术/假装你知道如何做事
(Noun) The art of bullshitting/faking like you know how to do something.
When faced with impossibly brutal homework one learns to perfect the concept of greasing.

"That test was very difficult" said Panjeet. "I had to employ much greasing to survive."