Teens often dress strangely, have piercings, and act rudely, but they can still be decent teenagers. Criticism will only cement the attraction. As parents, you have to ask yourself why you do not like these friends. Is your teen suddenly losing interest in school or activities he or she teen once enjoyed? Are these new friendships escalating the rebellion at home? If not, then hopefully, like many teenage actions, this is just a passing phase. However, if your teen is starting to fail, you can talk with your teen about the change in behavior. Parents can express concern, ask pointed questions about schoolwork or why the teen no longer enjoys the activity. If talking does not yield any answers or address the behavior problems, do not be afraid to ask professional help to assist you in addressing the negative behavior.