If Someone's Romantic Partner Dies, Avoid Celebrating
We know how hard dating can be, but before you celebrate someone's newly "available" status too publicly, make sure they're single because of something like a mutually agreed upon breakup. Not due to something like, you know, death.
Keep Your Sex Life Private
If you, like Mark here, get embarrassed about your mom 'Liking' the fact that you finally got laid, either unfriend her or stop boasting about your sex life on the Internet.
Your Boss Is Not Your Friend. Do Not Friend Your Boss.
There's never a good reason to add your boss on Facebook, but if you do, try and refrain from calling him a "wanker," as this dedicated employee did.
Do Not Deliver Bad News to Your Children Via Status Update
Divorce is hard enough on the kids as it is, so please talk to them first before telling everyone via a ridiculous social networking site.