The first time I saw this film I hated it, thought it was vile, hateful, manipulative in the worst way. Two incredibly likable actors playing hateful characters. I felt violated. I just didn't get the perspective of the humor, I think, because it is not what it seems at first at all.
I saw it again recently and since I knew what it was, I loved it. This is one of my favorite scenes:
embedding disabled so click through