I am not a sociology or social psychology expert but peer pressure is very great amongst teenagers. In informal social situations, making friends and keeping those friends can mean that an individual make conform to the their friends requests, they might behave in a nasty way if their friends done do that they want. Think of Mean Girls......many teenagers want to fit in and want to be liked. So in order to have a large group of friends and be popular a individual will comply to the behaviours of their friendship group and also what teenage culture and even the media wants and expects. If you do not succumb to peer pressure you are a very strong individual for that individual will be ostrasized from the friendship group or from the cool kids are rejected by their peers in general. Peer pressure can be so extreme that it can end up turning into a social tribe and subculture. So an individual, feeling the pressure of the group and fearful of the consequences - rejection - will start to behave the same way the others do in their group of friends or general teenage culture.
Examples many include trying drugs to fit in and to be Cool. Leaping from on balcony to another in those party holidays for teenagers and young twenty somethings. That is a good craze. Some people who where egged on by their friends, did that craze (sorry I do not know the slang term for it) have died trying to be cool; having sex for the first time so be fit in with your friends and peers even though you where not ready and you get pregnant or a STI. Egged on to that stupid internet game where you down drinks online and film yourself and some might cyber bully people or their ex-friends to fit in and to be cool. People feel they have to get very drunk to fit in with their peers and some now have developed problems with their liver in their twenties because of the pressure to be cool and drink
Personally, I think fitting in sucks. Why do teenagers have to do these type of things to fit in. The problem is that in many cases if you dont fit in for whatever reason or refuse to, you will be bullied by people. I think it is better to be yourself and choose what you want to do and not follow the crowd, especially if you do not like or agree with what others are doing. But in doing so, you get a lot of flack from the sheep who succumb to peer pressure. When I was at school, everyone know everyone else's business as it was a small Academy with only 600 students. And basically if you didn't lose your virginity bang on at the age of consent you got accused of being Gay or Lesbian and because I didn't, I was branded a lesbian and on one would sit next to me or talk to me. It was difficult but I kind of started laughing at them slags and sleeze balls who where calling me names, because they where sad and pathetic and ignorant - they thought that a lesbian was some who didn't loose their virginity LOL thought it was a female who was sexually attracted to other females...LOL.
At the end of the day, if a friend cannot accept you for who you are, then they aren't your friends. Unfortunately there are al ot of fair weather friends who will only like you if you act the same as them.....