A curious staple of UK television, Come Dine with Me is a reality show that features a group of strangers competing to throw the best dinner party. Contestants each take turns hosting the others, subjecting their competitors to an evening of food, conversation and entertainment. The guests mark each other out of 10 and the winner gets a cash prize. As with many reality shows, the producers seem to select the contestants with the aim of generating conflict, but a cringe-inducing sense of awkwardness peaks—quite regularly—when a host makes the evening entirely about themselves: “Why wouldn’t everyone want to see a slideshow of my niece’s graduation?” Or, “Just wait until you see what I learned in my burlesque class.”

Take note: Effective entertaining never centers on the h...