What Is Choo Choo? Choo Choo Is A Cat is a book written that includes real life photos of an adorable grey and white mischievous cat. Choo Choo is very photogenic and his book will include pictures of him as a 5 1/2 week old kitten that is the size of a butter stick, to a full grown cat of 3 years old. You will see him in his favorite places to sleep, his white tuxedo coloring, and his adorable pink nose. I know you will fall in love with him as I have, so enjoy the pictures!