Just a few more, in no random order:
LIKE WATER OFF A DUCK’S BACK – Has anyone ever poured water on a duck to test this? Last I noticed, ducks still get wet. I’m not aware that ducks have a teflon coating.
I DON’T GIVE A RAT’S ASS – Well, if the point is to convey you don’t care, then I suppose this would qualify. By saying this, you’re actually saying that you don’t care enough about something to even give the butt of a verminous rodent for it. Even so, I’m trying think when in our history were rat butts ever considered a form of currency.
IT’S NOT ROCKET SCIENCE – Please, like rocket science is that hard. If you had a degree in rocket scientology, you could build those things all the time.
WITH ALL DUE RESPECT – People usually say this right before they say something disrespectful. “With all due respect sir, you smell like the business end of an elephant on a hot August day.”
YOU CAN’T TAKE IT WITH YOU – Used to convey the message to people they should spend their money now because they can’t spend it when they’re gone, i.e. “you can’t take it with you.” Although, that’s not really accurate because Egyptian Pharaohs took their stuff with them all the time.
Bookshelf Battle 
I love “with all due respect” because I think it’s really a subtle insult… i.e. I will give you exactly the amount of respect I believe is due to you, but that amount may be very small. The author Lemony Snicket signs off this way in all his letters to readers. And I don’t know; the back half of a rat is the half that isn’t smashed under the trap, maybe? I wonder if that one is more about how the words sound together than the actual meaning.