This whole article is fascinating, but I do have to correct you here - "nah" is universal.

I used to say it for a long time, and I grew up in London, Vienna, Montreal and Ottawa with really no American Black people around (Island people, yes, but they have a completely different vernacular).

I stopped doing it because it sounded unprofessional. I only heard about the Rosa Parks connection from you!

Thanks as always for an eye-opening article.