IIRC when Austin first started using What it was pretty awkward and fan were trying to figure out what the fuck he was trying to do. I think it wasn't until he became a face again that it became the phenom it was and is.
That sounds right. What sucks about it is how many promos are doomed to fail because their momentum is broken by the constant chants. It's fine for the occasional heel promo or when a promo is already bombing or not making any sense.... Hmm, could've been useful during the days of the Ultimate Warrior (much as I was a mark back then). Speaking of phenoms, the "WHAT?!" chants have allowed the Undertaker to be rather creative with his responses over the years. Vince McMahon, too. Ultimately, I think the only person who can truly do "WHAT?!" any justice is the person who started the craze, Stone Cold Steve Austin. Maybe CM Punk, but even then just to throw it back at Austin as he has before on at least one occasion.