My family had a major falling out with my father, to the point where myself and my sister had a restraining order against him when I was 7 and she was 9. I haven't seen him or talked to him in 16 years. After Facebook deleted my privacy settings, I had a message from him sitting in my inbox the next day. My sister called me, crying, because she had gotten the same message. Both of our accounts were previously unsearchable on the site, with all of our data being private. As soon as they rescinded that privacy, our father could tell what cities we live in (in one of our cases, a _very_ small town) and that she had gotten married, we both had changed our first and last names, and one of us had a child. He found me through my mom's friends list, he found my sister through my friends list. All of which were previously hidden.

Nothing came of it besides an unwanted "please call me" message from him, but it's not a far reach from there to actually being located physically and confronted. We sent this man to jail and changed our names to keep away from him, and Facebook, in spite of their "privacy" settings, let him get a glimpse back into our lives.