All teenagers have been warned: “don’t give into peer pressure.” We hear that peer pressure can do things like lead to drugs and binge drinking and unplanned pregnancies. Maybe peer pressure will make you drop out of school and join a gang. But in Tina Rosenberg’s opinion, peer pressure isn’t all bad. The Pulitzer Prize-winner is the author of a new book called “Join the Club: How Peer Pressure Can Transform the World.” She argues that peer pressure is a very versatile tool.