Y'all gives way to my favorite word, Y'all'd've (You all would have). It it fun to say and wraps up so many grammatical concepts into a neat package. Example usage "It's too bad Y'all didn't come to the party, Y'all'd've had fun"
y'all'd've: y=second person, all=plural, d=subjunctive, ve=posessive
Fun to see stuff like this pop up where it usually doesn't.