First- "Hey Mom, did you know the author of this book is the same as The Sti...nky Cheese Man!? I wonder what else he's written." I sense another trip to the library in our very near future. :)
Then, at the end of the book the main character turns two halves into a whole, then jumps through the "hole". Josh said something like, "Its funny how they do that with the words. I mean, they're two different things!" So we talked about how words that sound the same but have different meanings are homophones, and how the author was making a play on words. Then we talked about how "homo" means "same", and "phone" means sound. That got us talking about prefixes and suffixes.
There are ways to painlessly work "lessons" into whatever your children are interested in. There is no need to force anything, let it happen organically. They're much more likely to retain the information that way also.