Ha! Yeah, but I also don't give books away, or if I do, they're books I haven't marked. I also never mark a book I borrow. That's a good way to lose a friend!I make marks to identify things that stick out to me, or things that I believe are important to the argument the author is making. I either draw a small star, or if something is really significant to me, I write an exclamation point. However, I never add any sort of explanation beyond that. If I want to make any explanatory notes, I will do that outside of the book.