That's a great line, I'll be sure to pull it out on Thanksgiving this year and see how it goes.

There are ways to counter this. For example, it can be said that Facebook isn't your bathroom. (Yes, this isn't exactly solid argument, sure.)

Still, I'm absolutely sure it's best to keep private stuff to oneself, and parties you trust. With understanding of full consequences of doing so. If one trusts Facebook, they'd better think why do they do so, as their trust may be misplaced.

I think one of problems is that when users post data they don't even think they send it to Facebook - they believe they send it to their friends there.

No, that's not an easy disarm. They just say "you're welcome to watch me poop".

I've been thinking about this. Having to prevent being observed is not without cost and many time is inconvenience and annoying. Why do I even need the door closed in the first place ? Because other people will I think I'm weird ? Is it cultural thing? Why do I have to feel embarrassed/ashamed when people see me in the bathroom ? What if as the society changes to become more open, the more people leave the door open, the more it become the norm, then I don't even need to care anymore whether the door is open or close when I'm using the bathroom.

"Oooh! How much do you make? How many sexual partners have you had? Have you ever cheated on any of your partners? Ever had an STD? Whom do you secretly dislike even though you don't show it? I've never met someone with nothing to hide before, this is so exciting!"