M is for Marmite.
...which is the easiest way to explain what Twitter is to most people.
I also like "its pointless, but so are blowjobs" and "at least I'm not getting poked every two bloody minutes"
N is for NoOb!
I'm sure you'll have all seen new Twitter users, unsure what to do, showing the same panic as a man stuck in a cave full of bears, covered in honey. So here's a quick guide that you can share with the Twitter virgins, busting their social networking hymen and making a big sticky mess on the bed of the internet...
1. Twitter allows you to send messages of up to 140 characters, there are tools that let you go over, eg. Twitlonger, but try not to get into bad habits. No-one will think any less of you if you abbreviated 'because' to 'bcoz' if it saves you going one letter over the limit.
2. Reply to people by typing '@username message' if you only want that user and your mutual followers to see it; 'message @username' if you're replying but want everyone to pay attention; don't type a reply without using including the @username, because no-one will know what you're on about.
3. To direct message someone type 'D username message' (note the lack of an @). When and why you use DMs is up to you, and ill probably go into it when I reach an appropriate letter in my A-Z.
4. Retweets - use this for sharing other users' tweets with your followers, use a retweet with comment option if you want to add a comment at the end (dont just put LOL though) or if you want to share both sides of a conversation in the same tweet (for example, a question & answer).
5. Spam. Block and report them the second they pop up in your follower list. Yes, I know you want to get to 30 followers ASAP, but do you really want a follower whose only interest is selling you a penis extension? Maybe you do. I don't though. Because I have a big Willy.
6. Brush your teeth twice a day.
7. Have fun, don't take Twitter too seriously, and remember the ultimate rule of Twitter - "if you don't follow @fudgecrumpet, then you don't do Twitter properly."
So, yeah, point new folk this way so they get off to a good start.
Oh, and easy way to spot a Twitter noob in real life - if they refer to themselves as ATusername, takes a good few months to get out of that habit...