metacognition: annotating for others

I know this is not a "school" project, but it is something I am currently working on that we do frequently in school: writing our thoughts and predictions in books for the speculation and dissection of others.
A girlfriend of mine recently gave me a book entitled "Looking for Alaska", and proposed that I write in it my thoughts and predictions, etc. so that she could read it and pass it around to other people. She hoped that then there would be a whole tapestry of ideas, of personalities, lacing this book and enriching the experience. I loved this idea; when i got home I started reading immediately and wrote very early in. I guess at first, my intent, my aim, was to make smart or personal remarks that would be 1) witty and/or 2) possibly charming. At first, I knew I was going to like this book because I found it easy to connect with the character, and I can rarely read books if I cannot connect to any central character. This connection, however, made it easier for me to write about personal things. Inside jokes, for example.
Some inside jokes and inferences that I probably would not want whoever would read it next to know, either.
I was surprised at the lack of privacy I was thus experiencing, and also surprised that I still did not care. This was supposed to be enjoyable for me, too, I thought, and so I censored little and wrote whatever came to my mind, for the most part. I could not believe it as I wrote this, because, though I am an artist who advocates self-expression, even for public expression, I am normally very vague in what I am trying to convey if it is at all public. This was not the case-- I wrote little notes to the girl who had given it to me, some inside jokes, whatever language or style of language I chose, and remained comfortable in the knowledge that someone would likely read this in the future--more interesting yet was that she would.
And I realized, if I felt insecure and withheld my true thoughts, that would be against the original concept of the group annotate of this book: to see the color range of people's emotions as they go through the literary journey, in all their comparisons and contrasts. I now knew that it was more so my duty than privilege to write my emotions and thoughts, and went ahead at full speed.