Transformers 2 was the first movie I've EVER walked out of. It was right after the US Army drops Optimus Prime's dead body from a helicopter and it clang around onscreen like a bag of CGI-typewriters. And get this... I wasn't the only person leaving the theater. Two points: 1) Optimus Prime is a warrior/hero and the US Army doesn't disrespect its fallen as such, 2) WTF? just lower his corpse to the ground gently. We wouldn't cut free an M1A1 tank so carelessly... and there isn't even a sentient lifeform residing there. GAH.
Everyone leaving the theater with me was like, "That was the final straw."