The contraction of the words "we" and "all"; similar to y'all. Pronounced slightly different from the word wall by starting to say "we" and immediately changing into "all".
Guy 1: I got my hiking boots on!
Guy 2: Okay. W'all ready?
You don't need to go all internet all caps to get your point across. If your logic is sound your point stands on it's merits, not the volume of your voice.