It has been five years since the last edition of Forbidden Broadway, titled Forbidden Broadway Comes Out Swinging. (It always did.) The long hiatus, however, hasn’t dulled the ruthlessness of Gerard Alessandrini, the Drama Desk–winning lyricist and director who satirizes a range of theater shows and foibles, often using classic show music with his own deft lyrics. And he has probably never been more ruthless than in Forbidden Broadway: The Next Generation. Smart, vicious and superbly cast, it’s sublime.