When I moved to Washington several years ago, a D.C. veteran whispered a warning that she had learned from her father: New York is tough, but Washington is mean. Truer words, my friend, truer words. Yet, apparently, even Washington can be offended by too much meanness. By now you’ve heard about the disastrous White House Correspondents’ Association dinner last Saturday, where comedian Michelle Wolf tortured her audience with lousy jokes in a tin-tongued voice that made one yearn for the sound of fingernails on a chalkboard.