The Captain Underpants series has been banned or challenged for several reasons including encouraging disruptive behavior, offensive language, insensitivity, violence, unsuitability for certain age groups, LGBTQ+ content, and encouraging children to disobey authority. Some specific controversies include the presence of a same-sex couple in one of the later books and a spin-off book, The Adventures of Ook and Gluk, which was withdrawn due to harmful racial stereotypes and passive racism. Despite these issues, the books contain no sex, profanity, nudity, drugs, or graphic violence, with most of the content being humorous and aimed at making children enjoy reading and questioning authority when appropriate.