An interesting read from Newsweek on "pluralistic ignorance" — where teens widely overestimate the behaviors of their peers and act out based on their mistaken perception of what's "normal."
I recommend reading the entire article, (click on the source link below).
One of the curious phenomena of adolescence is the way teens compare what risky behavior they're getting away with against what their friends are getting away with. This should be a straightforward process; to the extent they drink together at parties, and text-message throughout the day and night, they should be accurately aware what the pack is up to.
Unfortunately, this is not how it works, according to Dr. Christopher Daddis of Ohio State University. Be they jock or goth, teens might know every detail of their best friend's life, but when they contemplate their peer group, they key off the traits of their clique leader - and these leaders usually are engaging in more risk behavior. In addition, adolescents boast to each other about what they've done, how crazy it was - but they're mostly mute about what they don't do. Hearing only the wild stories, teens derive a very skewed picture of what their friends are enjoying.