Generally used after naming and shaming some one or thing, giving permission for the listener to compile their own mental list of those who can be attibuted to the ghastly deed.
The lyrics of this song (spaced out) are often used to remind a content's incest meaning, since it's a stereotype for Alabama people to not really care about the girl being their cousin.
Joe: "It was my sistah's birthday, so i kissed her as a gift!"
Dick: "s w e e t h o m e a l a b a m a!"