"Waiter, fetch me a bowl of your best custard!" he tells his human. And when his owner doesn't do anything, he looks up at him and thinks "Well, what are you waiting for? Haven't I made myself clear?"
For the rest of the book, we follow Kevin around as he tries harder and harder to communicate to his owners what he wants.
The Cat Wants Custard was a hilarious look into the mind of a cat. There was a lot of affection towards cats in this book. If you own (or have owned) cats then the Cat Wants Custard will definitely get a reaction out of you.