A couple of years ago, my cousin made a post about copying a CD or downloading a song; something along those lines. My mother reads this and posts "NO DON'T DO THAT IT'S ILLEGAL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
My cousin promptly deleted my mother, who was shocked by this action.

I have some older family members added, but they never post, and since I barely post as it is, it doesn't really bother me. I'm pretty satisfied with message boards, where you can post whatever and act like a tool, and generally not have to worry about this causing any problems in real life.
For the most part, I find FB pretty fucking boring and annoying -I hate getting messaged by people I don't want to talk to, but turning off chat solves that- but it is nice to be able to keep up with people who don't live near or haven't seen in a long time, I guess. Plus not everybody cares about dicking around on boards.