I have learned to agree with anything they say, and I'm not necessarily sarcastic about it. I throw in a smile, too. Inside I'm seething, but outwardly I don't let it show how angry I am. I think they thrive on our pain and worry, and I don't give them the satisfaction.
I have had several horrific bosses, but as soon as I have said, "You know, you're right," they have had nothing more to say. What could they say? I find it's good to buck up their self-esteem every now and then, you know, make them feel special.
My favorite terrible boss had no eyebrows. None. I felt sorry for her and often complimented her on her artistic skills. For seven years I honestly think she thought I was complimenting the decor in her office. She never knew I was commending her for how well she drew in her eyebrows.
Thus, handle a "terror boss" with care and a great deal of interior humor.