I live in Texas, and it's really annoying when someone says "y'all'd've" when they really mean "y'all'd've'ff've". Smh like, learn some grammar people.
Since everyone seem pretty rightly upset about the "y'all'd've'ff've" I instead present to you another Southernism that makes more sense and is actually in active use.
Y'all'd'n't've
"Y'all'd'n't've done that if'n ya knew what the consequences were gonna be."
Frodo: Hello. My name is Frodo. l am a Hobbit. How are you?
Legolas: y'alld've'ff've
Frodo, crying: please I can't understand what you'r saying
This strikes a chord....this was basically me when I moved to Scotland. I'm a bit over 2 years in, and there's still times I have to ask people to repeat themselves....