Most of us are really careful about what we share on Facebook. But one part of your FB profile ISN'T in your control -- your wall! People can write anything they want on your wall for the whole world to see -- no matter how embarrassing it is or how bad it might screw you over.

Here are two things you should NEVER do on FB:

Don't dirty up a friend's wall. You might not count your mom, your boss or little cousin among your Facebook friends, but that doesn't mean your friends do the same. Using curse words or mentioning a friend's naughty behavior is totally unclassy. If she's a raging partier who drinks 10 martinis and dances on the bar on Saturday nights, let her be the one to admit it!

Don't blow an announcement. OMG! Your friend Joe just proposed to his girlfriend! You run to congratulate him on his wall. But what if the happy couple is calling loved ones to personally give them the big news? Your wall post could get Joe in big trouble with his friends and relatives. (This goes for bad news, too -- major events like breakups or getting fired should be announced by the person involved, not by their friends.)