Teenagers who do dangerous thinks are trying themselves. When you have passed childhood and become a teenager, you believe you can do whatever you want, specially with your body, and you can think there are no limits. You want to feel alive! More, you want to achieve a status on your group of friends, sometimes “over” them.
Even thought, become teenager doesn’t mind become stupid too. Lift-surfing could seem an exciting way to get fun, but if you throw out any kind of caution and put yourself into a risk situation, you are unbrained, irresponsible and foolish.