Trivia / The Adventures of Ook and Gluk: Kung-Fu Cavemen from the Future

• Bury Your Art: In the wake of an increase in hate crimes against Asian-Americans and Pacific Islanders in 2021, Pilkey expressed regret towards The Adventures of Ook and Gluk: Kung-Fu Cavemen From the Future for having "harmful racial stereotypes and passively racist imagery" against Asians and had the book pulled from print.
• Development Hell: The end of the book teased a sequel called The Adventures of Ook and Gluk Jr.: Kung-Fu Cavekids in Outer Space, which was supposed to be "Coming Soon-ish!!!" This may, however, have been a Lampshade Hanging of the earlier two instances of Development Hell for the Captain Underpants series. And considering that the original was eventually pulled off the shelves due to controversy, a sequel is pretty much impossible.
• Keep Circulating the Tapes: This book was removed from the market and some libraries in 2021, for depictions of offensive Asian stereotypes, with the only legal way to obtain it now being to seek out used copies.
• Stillborn Franchise: A sequel was teased at the end of this book, but due to apparent Development Hell for over 10 years and after the first book was pulled from the market in the wake of Asian-American racist attacks, the follow-up naturally never saw the light of the day. However, Ook, Gluk, and Lily had an appearance in a comic in Captain Underpants and the Revolting Revenge of the Radioactive Robo-Boxers.

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