Little boy Mr.Bean has a lot of questions in his head. When mom and dad tell him to brush teeth, he would think of many animals who do not brush their teeth. Then he ask "Why hippo does not brush his teeth?" The twins who called "Teeth Broker" slip into Mr.Bean's book and try to steal delicious meals which is food chippings in animals' mouth. Along with Mr.Bean's bunch of question about why animals do not brush their teeth, the brokers start their advance through animals' mouths and teech at the same time. This book is very interesting and funny. Readers could learn about teeth-brushing habbits, animals scientific knowledge in the book.