When I was a child the regional differences in accent were so great that some groups couldn't understand each other's speech easily or in some cases, at all. Deep South African-American on the one hand and New York City on the other would be a good example, particularly if the NYC person used a lot of Yiddish slang. Things have evened out a bit, but the differences are still there. Medial liquids disappear in some dialects, so you get the Coats instead of the Colts for example.