From Resident Evil 5 (I know it's an easy target, but anyway), some dialogue I found just so laughably bad was in a cut scene at the end of the mission where your just using a machine on a jeep and you've just killed a giant mutant thing ...
Paraphrasing a bit here ...
Sheva "This shit is crazy. We need to get out of here."
Chris "No I need to find Jill so the story and game can continue."
Sheva "Your right, I'll come with."
Chris "No, you leave. It's too dangerous for you, despite the fact that you come through to this far."
Sheva "No, I'm going to help you. These are my people, you know, because I'm Afircan."
I just thought, "WTF, you've just gone from being piss scared and wanting to run crying home to mum to wanting to selflessly help your fellow man and save the world." It made me lol.