The "Captain Underpants" books were reported by the American Library Association to be the most frequently challenged books in 2002, 2004, 2005, 2012, 2013, and 2018, and ultimately became the second-most banned book in the United States between 2010 and 2019. Dav Pilkey also mentioned this in his website. According to the American Library Association, Pilkey's Captain Underpants series was explicitly banned in some schools for insensitivity, offensive language, encouraging disruptive behavior, LGBTQIA+ issues, violence, being unsuited to the age group, sexually-explicit content, anti-family content, as well as encouraging children to disobey authority.