The expression, "everybody's doing it," is very much at the center of the concept of peer pressure. It is a social influence applied on an individual in order to get that person to act or behave in a similar way as a larger group.
People are social creatures by nature, and so it is hardly surprising that some part of their self-respect comes from the approval of others. This instinct explains why the approval of peers, or the fear of disapproval, is such a powerful force in many people's lives. This instinct drives people to dress one way at home and another way at work, or to answer a simple "fine" when a stranger asks "how are you?" even if it is not necessarily true.
For certain individuals, seeking social acceptance is so important that it becomes an addiction. Teens and young adults may feel forced to smoke, or drink alcohol, which might encourage criminal behavior. Mature adults may sometimes feel pressured to cover up illegal activity at the company where they work, or end up in debt because they are unable to hold back the desire to buy a house or car that they can't afford in an effort to keep up with the peers.
However, peer pressure is not always negative. A student whose friends are good at academics may be urged to work harder and get good grades. Players on a sports team may feel driven to play harder in order to help the team win. This type of influence can also get a friend off smoking, or to help an adult take up a good habit or drop a bad one.
Although peer pressure is sometimes quite obvious, it can also be so subtle that a person may not even notice that it is affecting his or her behavior. For this reason, when making important decisions, simply going with an instinct is risky. Instead, people should seriously consider why they feel drawn to taking a particular action, or it is simply because everyone else is doing the same thing.