Having recently moved to the South (from IL to TN), I have definitely noticed some differences between southern vocabulary and northern vocabulary. Here are a few of the words and phrases that I have heard that are definitely southern.
buggy (n.) – shopping cart
Knoxvull (n.) – Knoxville; note: any city name ending in -ville is pronounced as -vull
Krystal (n.) – an alternative to White Castle with equally greasy and questionable food
fixin’ to (v.) – getting ready to, preparing for, about to; example: “He is fixin’ to go to the store.”
y’all (or ya’ll) (pl. n.) – form of you all, denotes two or more people
all y’all (pl. n.) – used with indicating individuals in a group
hon (n.) – used in place of Miss or ma’am, any female; example: “Well sure, hon, we can do that for ya!”
I’m just saying… (phrase) – usually used after a statement to somewhat soften the abruptness, similar in meaning to “Well, that’s just my opinion…”
Bless her heart… (phrase) – generally not used as a compliment; example: “She’s gained 20 pounds in the past month! Bless her heart….”
soda (n.) – general term for any soft drink
Coke (n.) – general term for any soft drink
A side note: some areas call it Coke, some call it soda – Knoxville, sorry – Knoxvull residents call it both. So to avoid confusion, I have adapted from using the generic word “pop” to calling it by the specific name – such as Mountain Dew (aka Sweet Nectar of Life).