I cringe every time I see that ad. That, and any ad for Boost Mobile, whose tag line is “Where you at?” When bad English is deliberately used in commercials, it gives it credibility and increases the likelihood of it becoming acceptable. IMHO, “ignorant” is not the same as “colloquial.”
I don’t think that’s the case here: the woman on the plane could have said “you better not!” in the same tone of voice, with the same look on her face, and still come across as plenty “black.”