[Congratulations Itachi, he snorts, turning his head to look at him with eyes bright with mirth.]

Oh, you're funny. [It's the delivery that does it for him. That and the realization that it is in fact a joke. He has a weakness for people who appear otherwise serious actually making jokes.]

Still, good to know. [He flashes Itachi with a grateful smile.] You're very helpful, you know, Itachi. I suppose this makes us friends now?