Your friends ask you to "teach others a lesson" on the surface, simply talk about others, give them a reason or criticize the meaning of a few words. It is really unclear whether it is a fight. Since you are friends with him, you can ask about the specific meaning and the existence of the problem, which is related to his personality and style of doing things. If not, you really don't want to refuse him directly and say you can't go because you have something to do. It depends on your usual friendship and cooperation. Good luck!