Blame it on the Pen

The other night, Sammy wanted me to read the book "Goodnight Moon" to him. He gave me the book and I noticed there were drawings on many of the pages. Here goes our conversation:

Rebecca : Sammy, did you write all over this book. You know you're not suppose to do that. We have to respect our books and keep it in good condition. Did you do this?

Sammy: No, mom. I didn't.

Rebecca: You didn't? Then who did?

Sammy: The pen.