Slang is just cheap language. The people who use it are simply painting a picture of who they are. They don't really care who knows how lazy they are. They don't strive to be excellent in who they are and what they portray.
in my opinion ... slang carries a very deep meaning .. other than the one in appearance and the one we know ..... this quote simply means that people speaking slang are characterized by spontaneity .. they are not tied by Etiquette or a way of behaving .. they care about their own opinions .. they look at life from a different prospective than us . life for them is too precious to frame it in a certain way ..... so they just go ahead in life and walk and talk as if it was their last day in life ... they are convinced that life is too short .. and every day counts so how about quitting the faking and living for real ???? of course by the shifting of cultures and societies ... slang language became more like a low life and a very despicable one ...