Irrespective of the age,peer pressure works in devilish ways for us but teenagers are more likely to succumb to the demands to those in their peer group to 'fit in'.
Drinking among teenagers is something that has become very common these days and many just do it for the heck of it and to look 'cool' in front of others,unaware of the bad habit they are developing in a race to fit in.
It is often at parties that the kind of vibe and environment there is,you see a lot of people drinking.This puts a mental pressure on people who do not drink to do so in order to sink in with the crowd.Often there is this one friend or colleague who just won't stop pestering you unless you took a drink.What these people do not understand is the concept of consent.But,you have to firmly say no because in this democracy noone can make you do anything,good or bad that you do not want to.So,instead of giving away an excuse only to go through the same pestering at the subsequent parties,it's better to put your perspective across and your choice to not drink.It will also teach the person in front of you a lesson to not do the same with any other who's reluctant to drink.