This guy is memorable just for the pure crazy. When he enters the scene, we can imagine everything turning from black and white into trippy Technicolor… he's just that nutso. He temporarily turns this serious documentary into a hilarious sitcom.
Cristophe is a perfect example of the self-hating black person. He worships the ground that white people walk on, but hates his own people. This is what he says when he sees the other black people on the bus:
"This place stinks. Damned punk niggers. Look at all of them—bunch of dirty punks—don't know how to dress. You don't deserve anything better. Mein Kampf! Do you speak German? No. You're ignorant. You make me sick." (10.72).
The entire time that Griffin interacts with him, Christophe spins a web of lies about his identity. Not only that, but he tends to make himself appear educated by spouting out bits of foreign languages and other things that he seems to have picked up. We get the impression that everyone else already knows Cristophe and his lying habits.
Even though he provides a lot of comic relief, in the end Cristophe is more sad than funny. He has accepted the negative imagery of black people that white racists have propagated. He thinks that they are stupid, boring, and even smell funny. So he attempts to make himself appear smarter, makes up stories to be more interesting, and even pretends that he's "not totally black" so that people can see that he's not like the other lame black people.
No, he's not like them. He's drunk the Kool-Aid, which means he's worse than them.