The term 'Paper Fatteners' refers to a type of insert used in the printing industry. These inserts are typically made of paper and are used to add bulk to a printed document, such as a magazine or book. They are usually placed between the pages of a publication to give it a thicker, more substantial feel. The term 'Paper Fatteners' is derived from the fact that these inserts add weight to the paper, making it appear thicker.