How do teenager girls get accepted in a group?

Last night at the dance, a woman came to the dance with her adult daughter. Her daughter was in town visiting, and wanted to go dancing.  I danced with Sarah several times.  I was talking with her about what she viewed as the social scene at the dance. She had noticed that a lot of women who are the better dancers hang out by the stage and DJ booth. I said it seems that way.  She then said something interesting.  How does a girl get accepted into that group?  She said that she heard that teenage girls share lip gloss.  Once they share the lip gloss, then they are part of the group.  I am not sure if the women at the dance do that.  I think it is more about they are taking the same classes, or on a team together, or they developed friendships through dancing.  I think it is more than lip gloss for teenagers too.  There needs to be a shared experience. Sharing lip gloss is more of the symbol.