The White House Correspondents' Dinner is supposed to be the hard-wired epicenter of American politics, an Insider’s Ball where the shame of admitting you’re the last to know something is a humiliation of Carrie-pig’s-blood-prom magnitude. Yet everywhere at the roses-and-Rolexes 2016 dinner you could hear squeals of collective ignorance and expressions of shock, feigned and real: How the hell did America let Donald Trump become the nominee of a major party?