The Thank You Book by Mo Willems

An exuberant character decides to thank everyone and sets out to write a book of thank-yous, enlisting their skeptical best friend as the list grows hilariously long; the pair include dozens of characters and objects, only to realize they've forgotten one very important recipient — the reader — and deliver a warm, fourth-wall-breaking thank-you that celebrates friendship, gratitude, and the joy of saying thanks.

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