Just a regular burger...no unique bells and whistles. But for some reason it's heaven on earth. Anyone who has ever had one will confirm. I've known people who will drive 45 minutes from suffolk county for one.
True story - one of my kitties that passed away a couple of years ago had a NOSE for burgers from all american. Any other fast food place and he'd be all "meh." But the second you walked in the door with all american he'd be rubbing up one you and purring like there's no tomorrow begging for some.