The book really, really exists, and you can verify it via show and tell at the First Second blog, thanks to Gina G! My favorite quote:
Can you believe that one of the people at our parent company had never
heard of the Barrel of Monkeys toys that our designer, Colleen AF
Venable, was modeling these on? We had to explain.
She’s referring to the back cover, which is So Very Fine. Click that link and you’ll agree!