In the past, the term “October Surprise” has almost always involved the Democrats turning up some last-minute dirt on a Republican. Perhaps the best-known of these was the revelation of a driving-while-under-the-influence charge (DWI) against Republican presidential candidate George W. Bush on Friday, November 3, 2000, a mere three days before the razor-thin 2000 election. Many political analysts think this cost Bush significant votes among evangelical Christians. But the “October Surprise” of the 2016 campaign was close: a video from an “Access Hollywood” interview with Billy Bush came out on October 7, 2016, in which Trump made comments about what...