1. Highlight at random, to befuddle the next lazy student with the book.
2. Use a black marker to mark out some passages. Write in the margins: "NO NO NO!! COMPLETELY WRONG!!".
3. Write in the margins notes that suggest a different subject. Example: In a Physics book, write: "Damned supply-side Reganomics"; in an Economics book, write: "That's what Decartes meant", in a Philosophy book, draw a trigonometric graph. You get the picture. Endless fun!
4. Rip out your favourite sections.
5. Write a distracting, and compulsively readable, romance novel in the margins.
6. Verbally threaten the next reader. Be sure to write, "I know where you live!"
7. Black out an important section, and paste on some meaningless dribble that kind of hints at what was being said.
8. Carry on an imaginary discourse with a figure in that area of study in the margins.
9. Write out the lyrics to "Louie Louie".
10. "Correct" grammatical "errors" and the like.
11. Write personal information about your own worst enemy.
12. Relate the text to obscure, or esoteric, or unrelated topics. For example, in a literature book with an eccentric character, write "Chicken Man!"
13. You have a favourite Devo song? No? Okay, then just write "Whip It" over and over again in the margins.
14. Draw horns on people's heads. (Note: Time-tested since Grade School!).
15. Later on and in the same book, draw horns over words.
16. Uh, that's enough. This list ceased being humourous and insightful a few things ago.
... why is the the Info Superhiway, especially email, full of junk like this?