The Reading Is Fun club is a club that Susan Heffley started for Greg Heffley, possibly as a punishment after he watched Hello, You're Dead. Susan decided to invite Greg's friends as well, because she thought that all boys Greg's age needed to read more because she felt reading was better than watching violent movies and playing video games, which is what she thought boys Greg's age did too much of. It could have been a punishment or she might have just been reminded of the prevalence of violent movies and video games because Greg had recently watched Hello, You're Dead and plays video games on the regular. Greg deeply disliked this idea and would have rather had a "regular punishment".
It appears in Diary of a Wimpy Kid: Dog Days (film) and the Diary of a Wimpy Kid: Dog Days novel. They read various classics chosen by Susan. The books brought to the club on the first day are Sudoku Insanity, Ultimate Video Game Cheats: Volume 8, Green Wasp, and Xtreme Pop-Up Sharks, although Susan is dissatisfied with their choices and instead brings out Little Women, The Yearling, Old Yeller, and Anne of Green Gables.
On the second day, the membership is down to Greg and Rowley Jefferson. Greg brings Shadowdoom, while Rowley brings How to Find Garden Faeries and Me & My Mommy: Silly Playgroup Activities. The classics are actually real life books.