There are tons of dialects and accents and group slang that the joke could be done with. Doing basic generational slang would likely flop, but you could easily use something like a thick accent from Texas like Boomhower in King of the Hill, or a Louisiana Creole accent, or some deep Appalacian accent, or some Spanglish.
1 is why I said or an equivalent - you could do the same with pidgin or any creole or, I don't know if this is a PC way to say it, but any kind of 'hood' or 'ghetto' type slang. The joke is just person is 'fluent' in an unlikely dialect/way of speaking. If cockney rhyming slang were more prevalent you could do that, with you know a black American or Asian person or whatever being the unlikely fluent one.
2 is is not really the point, sure it could flop, my point was just that I couldn't imagine it going further than that, not that that would be funny.