PEER PRESSURE

Peer Pressure is when you're pressured by a group, this becomes an important influence during adolescence, usually to fit in or to be "cool".

This happens because they´re at a stage of development, starting to be less influenced by their parents, but have not established their values and the consequences of being influenced by their "peers". Not only that but also because teens strive for social acceptance, wich then in most cases results in them being in a group and following their rules/ideas without thinking about it.