Rep. Adam Schiff — along with “Crooked Hillary Clinton,” “Cryin’ Chuck Schumer” and “Crazy Maxine Waters” — has long been a target of mockery on Donald Trump’s Twitter feed. But in a post Sunday, the president may have coined his crudest nickname yet for a political rival. “So funny to see little Adam Schitt (D-CA) talking about the fact that Acting Attorney General Matt Whitaker was not approved by the Senate,” the president wrote online, “but not mentioning the fact that Bob Mueller (who is highly conflicted) was not approved by the Senate!” Schiff fired back 35 minutes later, quoting...