The Cracker Barrel customer had a checkbook, and what he wrote in it after lunch Thursday would make his happy server even happier, but first he and his friend had a few questions. They asked the hostess: Can you give us your grumpiest server? We want to make them laugh. Sorry, the hostess said. Nobody grumpy here. I’ll seat you with our happiest. At Table 222, they asked Abigail Sailors for the special — turkey and dressing — and for eggs and sausage. Then they asked the 18-year-old why she was so happy. And over the course of their meals,...