Neil Bernstein is a psychologist who writes about how to understand peer pressure, sex and to talk to teenagers about how to deal with it, if they ever come across it in their lifetime, which they will. He wrote a book called, "How to Keep Your Teenagers Out of Trouble and What to Do if You Can’t".
"No influence in your teenager’s life is as powerful as peer pressure."
He talks about what types of pressure teenagers go through, the first being sex because at our teenage years that's when we learn more about it and understand it, and start to have sex too.
Basically anyone who pressures us to do something we don't want to do is the wrong thing.