Sir, 'tis my occupation to be plain. I have seen better faces in my time Than stands on any shoulder that I see Before me now at this instant. (2.2.18)
Ooh, burn! After Kent strikes Oswald (because he doesn't like Oswald's face), he explains to Cornwall that it's just his personality to be blunt ("plain"), which is why he's being honest with Cornwall now when he says that he doesn't like the looks of Cornwall's face either. (What? Who says Shakespeare can't indulge himself by writing a little trash talk into his scenes?) For Kent, being completely honest and speaking the truth is a matter of pride, even if his big mouth gets him into trouble. So, even if we fault Kent for being so ridiculously loyal to King Lear, we've got to give him props for being so truthful.