Learn to keep your mouth shut
The OP shared a story that his foolish coworker experienced. The coworker waited on a man and a woman, and the three of them were really clicking. That’s not something you usually see at restaurants, but hey, if you can work and make new friends at the same time, why not, right?
Anyway, fast forward two months, and the male patron was back again. He specifically requested that the OP’s coworker wait on his table again. The coworker greets the man and his date and tells them that he enjoyed serving the pair last time. Turns out that last time, the man was out with his mistress. This time around, he was dining with his wife. Some people really don’t know when to shut their mouths.