Tiffany Carandang, 17, had been with her boyfriend for months. They loved each other and trusted each other completely. So it was only natural when they took the next natural step in their relationship: They exchanged Facebook passwords. “It’s a sign of trust,” Tiffany says. “I have nothing to hide from him, and he has nothing to hide from me.”  Sharing passwords to social networks or e-mail accounts is relatively common among serious teen couples or sometimes even amongst good friends. To exchange passwords suggests complete trust and commitment; but some teens have said they’ve felt pressured to exchange passwords, and if a relationship goes south, a vengeful ex could wreak havoc with someone’s Facebook or e-mail account. Most experts warn against sharing passwords, but few see the trend turning around anytime soon. “What worries me is we haven’t done a very good job at stopping kids from having sex,” says Patti Cole, a child psychologist. “So I’m not real confident about how much we can change this behavior.” (New York Times)