Can I order the 9th and 10th Captain Underpants books?

Yes, you can order the 9th and 10th books in the Captain Underpants series, titled "Captain Underpants and the Terrifying Return of Tippy Tinkletrousers" and "Captain Underpants and the Revolting Revenge of the Radioactive Robo-Boxers," respectively. These books are widely available through various online retailers, bookstores, and libraries. Be sure to check the availability at your preferred source.