Things that you can do in letters.

1. Be insulting.
e.g You've had a cock up your arse then in your mouth. Therefore you can wash your face in the sink at my place as i don't have any toilet paper.

2. be gloomy and depondent
e.g. You might as well set fire to this letter without reading it.

3. be irksome
3 e.g. How do you suppose your house gets warm in the winter? 

4. categorise all sorts of stuff
e.g. fill this in yourself

5, be amusing
e.g. does anybody know if the library's open?

6. wrap it up as some kind of story referencing the start
e.g. You could always recycle this letter as toilet paper.

7. P.S.
e.g. applaud the modus operandi