I hate the sayings "you can't have your cake and eat it too" and "you made your bed, now go lie in it." I know what they are supposed to mean, but they sound so stupid to me. If I have cake, I'm going to eat the mudder fudder. If I made my bed, I'm not going to lie in it...not right away.
I also hate "it is what it is." No, shush, Sherlock! Of course it is!