How are social groups treated accordingly when all social groups are infinitely divisible?

Well what I do around my school in high school I go to my group of riends and say whats up and hang around or ping in the hall way I might stop to say whats up or talk for a few minuts my group Nerds and Jocks just like that we all about listen to the same kind of music and hang like AC/DC and all kinds country a lot of differnt kinds.