Southernisms: some of these are pretty antiquated, but I heard them from my grandparents
"fixin' to" is pronounced "fixinna"
calling young women by their first and second names: "Nancy Sue," "Clara 'Lizabeth," etc
Honey: what the waitresses call you
Sirp: syrup, pronounced as one syllable, as in: "Honey, you want some sirp with those pancakes?"
Greens: collard greens
Soft drinks: what we used to call carbonated beverages, I think it's been replaced by 'soda' these days. But not 'pop.' Pop is your father or grandfather.
Meemaw: grandmother
Papaw: grandfather
the john: restroom
the pokey: jail
hit the hay: go to bed
Others:
clam up, put a sock in it: be quiet
sh*t on a shingle: cream chipped beef on toast
dipwad, dips**t: stupid person
Epithets made up by my group in Madrid because we didn't know any Spanish curses:
Cacahuates
Cabeza Potate
I had an Australian fellow try to ask me for something, when I had my first job in a fast food restaurant when I was 17. He came up and asked me for some "auta." I looked puzzled, I guess. "Auta," he repeated. "Ya know, aitch-two-oh."