A term of endearment in the Yiddish language. Bubby is an accepted alternative. Used primarily in places where there's a high concentration of Jews like in New York City.
The rural American South, actually parts of the southeastern states Arkansas, Louisiana, Mississippi, Alabama, Georgia, Tennessee, North and South Carolina, Virginia, Northern Florida, a piece of eastern Texas, Kentucky and debatably, parts of West Virginia.
Huntsville, Alabama is fairly mainstream America, but once you get south of the Tennessee River, you're in Bubbaland.