People do things on Facebook that they'd never dream of doing in real life:

Love them or hate them, social networking sites are here to stay. Facebook and MySpace are among the most popular destinations on the web. And even though they can be extremely annoying, there is one inescapable fact: the most irritating thing about Facebook is the 100m-strong army of people who use it.

When was the last thing you looked at your feed without someone posting an embarrassing picture, or someone else saying something irritating in their status update?

Here are the top 15 things you should never do on Facebook or MySpace:

1. Use Facebook mail instead of proper email

Are you silly? When you Facebook mail me, I have to log into my real email to find that I then have to go and log into my Facebook account to read and reply to your message. If you've got my real email address, please use it.

2. Add old friends and then forget about them

This is the biggest social networking crime of them all. How many times has it happened? You haven't seen someone for 20 years; you vaguely recognise their name but not their face. They add you as a friend on Facebook and then after you accept them, you never hear from them again.

3. Adding people you don't even know

It's one thing to add an old friend and then never speak to them. It's another to add anyone whose name you kind of vaguely sort of recognise. It's like that old man in the pub who slaps everyone on the back as if they were old pals, when in actual fact he has no friends, largely because of this habit.

4. Adding single-serving holiday friends

Some people just don't understand that the exchanging of email addresses at the end of a holiday is just a social ritual and is absolutely not an invitation to add you to Facebook and then turn up unannounced at your house three months later.

5. Accepting friend invitations from people you don't know

It's one thing to complain about irritating people adding you on Facebook, but if you accept those invites, you've only got yourself to blame. If you scan through your Facebook friends list, you'll doubtless find a handful of people in there you barely know. It's a horrible realisation - like when you suddenly realise your hand is resting on a knob of someone else's chewing gum underneath a desk.

6. Update Facebook profile when you're supposedly ill

How many times have we seen it? Someone calls in sick in the morning and then updates their Facebook profile minute-by-minute throughout the day, documenting a day of ice cream, chips, video games and jumping on the bed. Get dressed and get to work you lazy hoodwink, or else you'll probably be fired. And it'd be your own fault for adding your boss to be your Facebook friend.

7. Write on a wall instead of communicating privately

The driving force behind the success of Facebook is... vanity. People love the idea that others are watching what they're doing. Tell me this: for what reason would you invite someone to a private party by writing on their wall, other than to show off to all the people on their friends list who you don't want to come? It just makes you look like a tit, so don't do it.

8. Moan in your Facebook status

The most annoying thing that people do on Facebook is to spray their walls with vanity-filled drivel, by posting self-indulgent awfulness in their status updates. "Kerry is sorry how it ended but it had to be done. I love you and will miss you, and I hope you can apologise one day". Oh sod off. If you've got something to say to someone, say it. Don't post it on your wall because no one else is interested, and people just think you're a prat.

9. Other irritating status updates

No, "Dave is" is not an acceptable status update, nor is it original or in any way clever. "Dave just is..." is equally as inexcusable. And "Dave is Dave is Dave" is downright taking the piss. Oh, and song lyrics are also a no-no. "Sandra was happy in the haze of a drunken hour, but heaven knows she's miserable now" will impress people about the same amount as Morrissey's saggy, miserable face.

10. Upload drunken pictures the morning after

Have a little common sense. If you go out for a big one on a Wednesday night, posting humiliating, drunken photos of your friends on Thursday morning is a recipe for disaster. Because when I call in sick at 9am, the last thing I want my boss to say is: "I've seen the pictures of you crawling in the gutter last night. I'm not amused or impressed, now get to work!"

11. Joining ridiculous chain-mail groups

Why do people insist on joining groups such as "On the X of May, everyone has to panic buy carrots"? Come on people, how stupid are you? There's one group on Facebook devoted to nullifying the vegetarian moral crusade, and it's called: "For every animal you don't eat, I'm going to eat three". That's a good group name. "I think Ryan Seacrest is the best presenter ever" is not.

12. Starting said groups

Enough said.

13. Lazy grammar and spelling mistrakes

Reading Facebook is like perusing a six-year olds' English copybook. Come on, people: ‘Your' is ‘your'. ‘You are' is ‘you're'. It really isn't hard to get that little one right. And understanding the difference between there, their and they're surely isn't too much of a challenge?

14. Upload photos to Facebook and deleting originals

Uploading photos to Facebook can be a very handy way of sharing your holiday snaps. But for the love of God, don't lose your originals. Facebook is terrible at compressing and resizing images - it turns your 14MP panoramas into 14KB monstrosities. Facebook is not a suitable repository to store your precious photos!

15. Inviting me to be a Zombie Pirate Snot Monster

Please don't do that ever ever again