In his new YouTube special, “Morbidly Jewish,” Raanan Hershberg explains that Germany has changed so much since World War II, you can now be imprisoned there for drawing a swastika. “Even though they are no longer Nazis,” he said, taking a beat, “they are kind of being Nazis about it.” Nazi jokes have a long tradition in Jewish comedy, flexible enough to include self-sabotaging Broadway musicals and stern soup salesmen. But what makes this one unusual — and gleefully perverse — is that it’s a Nazi joke about overreacting to antisemitism. That’s a twist. Hershberg has become one of the...