I am honored to be able to talk about one of the greatest words in the english language. Y'all. I absolutely love the word. I think of all sayings or words this is the one that identifies someone as Southern more than any other. It is the contraction of you all. Many people misspell the word as ya'll. This is wrong however.
I know many northerners that have come down to the South and will accept listening to country music or doing something else that is mostly Southern, but they refuse to say the word y'all. They say "you guys" instead hoping to hold onto the last bit of their northern identity. It seems like the deciding factor to if you are Southern or northern is if you say y'all or "you guys". We all take pride in the way we refer to others.
Since y'all is so commonly associated with being Southern, it is even the name of a Southern magazine, Y'all: The Magazine of Southern People.

It's such a great Southern word because it begs to be said with a Southern drawl. You cannot say it properly without dragging it out and saying "Yawl". It even made it into Rush Hour when Chris Tucker was trying to teach Jackie Chan how to say y'all properly.