Because they have trouble focusing mentally after all the meth and other lovely wonderful high grade narcotics kick in.
Or they're fucking batshit and you really need to keep your distance or get stabbed.
Like I'm in class right now, and this black lady is answering questions that arent even posed to to her, answering all the rhetorical questions and repeating everything fuckin thing the professor says while humming to herself.
Then in a different class a black guy answers questions real quietly and then mumbles complaints about how he didn't get picked.
I've only seen this sort of incessant verbal in black people.
Well I know theres mental disorders where you have a complete inability to keep thoughts in your head. The moment it pops in your head out it goes. I highly doubt its the case there though, they're usually highly unstable and prone to fits of neurotic behavior.
They're probably either so damn stupid its the only way to think or were never taught that it's possible to read and think without speaking, or high as a fucking kite and would cause a drug test to spontaneously combust.
Not all of them. I mean if I saw a white guy yammering to himself while walking down the street I'd be slightly more perturbed than if a black guy did it. That's just because it's more common to see a black people talking to themselves. It's not that black people are crazy, they just REALLY love talking for some reason.
just a stupid devil joke.
More seriously. She could be dyslexic, as dislexic people dont have inner speech (though it's usually limited to just movement of the lips). She could also be doing it as a method of memorizing. Or hoping she gets noticed by the teacher. or she's crazy or a combination of the previous. in other cases it can also be used as a method of coping (usually to vent)