As far as decadant foods go, I love the po' boy. It's not at the level of a Luther Burger or anything, but it's delicious.
I went to Tulane (poor Tulane.) and a staple down south is the po' boy. Basically their word for a sub or hero down there, but it traditionally incoporates some type of deep fried foodstuff as meat, usually fried shrimp, oysters or chicken. Also it's usually served on a nice, crusty french bread. with lettuce, tomatoes and sauce. A good fried shrimp po' boy is just delicious.
The worst I've seen is the French Fry po' boy. It's dirt cheap, usually like two dollars. A 12" sub with french fries and gravy. That's fucking it. Totally the thing you eat when you are dirt poor and need massive caloric intake for cheap.