Now used as a nickname for Atlanta. Origianlly used as a nickname for the Federal Penitentiary in Atlanta which used to be the maximum security penitentiary in the country and is where famous mafia gangsters such as Al Capone were locked up. Located at the end of Boulevard in Atalanta in one of the more dangerous neighborhoods. Also called simply "the pen" by locals.
What happened to Mike?
He got locked up in the A
Big Boi: If you want me you can find me in the A - Atlanta reference