When someone of any color hangs out with white people so long that their speech, style, and food preferences no longer indicate their heritage. Perhaps a more offensive way to say "Americanized".
A WhiteKnight is someone who pretends he is british, while he is really Indian. Constantly will hate on the French while having a massive respect for French culture and customs.
"Hey, is he still pretending he's British?"
"Yeah, I don't know who WhiteKnight thinks he's fooling"
"hey whiteknight"