That’s an actual Jim Davis quote, in case you were wondering.
One rule I made for this book, where I talk a lot about other artists, is that I didn’t put words in anybody’s mouth. I didn’t want to footnote everything, because it is a work with hundreds of references to other works and real people, and you don’t explain all the references and jokes in your own book. But when I show a real person with a word balloon, it should be understood that it’s something they actually said. The exception to that is with characters that are featured in things that are obviously fantasy sequences, like Jim Davis with Bill Watterson locked up in a basement. I assume people will get where one stops and the other begins, as Jim Davis does not actually have Bill Watterson locked up in a basement somewhere. As far as we know.