Kinda related... I grew up in an semi-affluent area in Alabama where pretty much literally everyone was middle-middle class or better (meaning, there wasn't a genuine "country boy" in my school). We were all well educated growing up and our English classes beat the "southern" out of us so we could pass as "Middle American" (or however it is they speak on TV).
So, a friend of mine in High School decided he was gonna roll with "Alabama man" and go full on "country" as a joke... and he stuck with it for like 2 years.
At some point he realized that "holy shit, this isn't a joke any more, it's how I talk now" and had to spend months retraining himself.
It was fascinating to watch.