It's like a voluntary Big Brother. For millions of teenagers, the Internet is like a drug. And the madness of the Internet and of adolescent hormones can be an especially potent combination. On one occasion, fourteen-year-old Kara met 18-year-old David on Myspace. The relationship, which began as a friendship, intensified on the site. When her parents, who opposed the relationship, tried to cut off her online access to him, her parents were shot dead by the boy.