Thomas Sowell did a great article on this that should be required reading for all 11 to 15 yr olds, black, white or asian. If nothing else only for them to be challenged intellectually on it. If they say "What do you know old man" so be it.
In it he argues how liberal teaching, that this slang is their culture (arx, innt etc) and therefore should be encouraged and recognisd is holding them back and doing them no service whatsover.
The same middle class elites that see no wrong in it wouldn't dream of encouraging their own children to adopt it.
From GCSE to A level, it's all changing