What’s the most embarrassing thing that happened when you sent a message to the wrong group?

There is an unforgettable thing that I experienced personally. It still feels so embarrassing. There are more than 100 people in our unit, so there is a large group in the unit. Each department below has established its own department group. Our department leader has a particularly good family background. In order to unite everyone and support his work more. Therefore, I often send a message in our department group and invite everyone to have dinner together in the evening. Normally, he would book a private room in advance and then buy some seafood he likes and take it for processing. Once, he organized a game at night. I went to the hotel to reserve a table in advance, but got an emergency notification at the last minute. Unit leaders visited various departments to learn about recent work plans. When the leader came, everyone said that he had just left. While sending him a WeChat message, he will be back within ten minutes under normal circumstances. It turns out that I sent it to him in the department group, and he replied back to the group in the unit. Moreover, he also said what kind of wine he had prepared in a certain private room on the fourth floor, and he also joked about a colleague in our department. And, he also said a few words about the boss. As a result, the entire unit knew. The leader also saw it, and he told the leader when he came back. How difficult was the customer just now? How could he handle it?