Every year, Tom Toles’s Halloween party draws an eclectic mix — journalists and political types from Washington’s power elite, but also artists and musicians, everyone from retirees to college kids, jammed into small rooms and sprawled across the backyard, dancing and gossiping, checking out the crowd to see who has the most inventive and outrageous costumes. At the 2018 party at the home of The Washington Post’s editorial cartoonist, in addition to several Ruth Bader Ginsburgs, someone dressed as the “Mueller Witch Hunt” and Post columnist Dana Milbank came as just-confirmed Supreme Court Justice Brett M. Kavanaugh, complete with a...