Captain Underpants and the Sensational Saga of Sir Stinks-A-Lot

A message from Dav Pilkey informs those reading that unlike previous books which appealed to both adults and children, this book will attempt to appeal to solely children.

On the planet called "Smart Earth", one scientist is mixing smart Diet Coke, smart Pop Rocks, and smart Mentos and this experiment cause Smart Earth to explode, one chunk lands in a grape garden causing the grapes to become smart, they try to wage war on humans but they dry out. Another chunk landed at the Piqua Valley Home for the Reality-Challenged. Gym teacher Meaner eats a chunk and becomes smart, he tries to walk out but two doctors block his way but he confuses them, and he and the other teachers escape. He then tells the other teachers that they must return to their jobs. Mr. Meaner turns an abandoned factory into his factory, and he makes a strange substance with sweaty gym socks called rid-o-kid 2000. Yesterday George and Harold are told to go to his office, at his office he sprays them with rid-o-kid 2000 and it turns them into robot-like slaves. The other teachers are amazed at their behavior, though other George and Harold are not, and they get sicker because of excessive homework. They see a commercial for the “Rid-O-Kid 2000” and disguise themselves as adults, making the children do silly things "for" the teachers. The teachers call in Mr. Meaner and enraged at what he sees, he gets out his Stinky Kong 2000, now a mech suit.

Deciding to seek help from adults they can trust, George and Harold go to their parents, only to find that they know they've changed and preferred it that way. Feeling heartbroken, they go to Melvin's house to find his Robo-Squid, then travel forward in time to find the older version of Yesterday George and Yesterday Harold, now famous graphic novel writers, and their families (we also find out that Yesterday George is in an interracial relationship and Yesterday Harold is gay/bisexual[2]), with whom they are also disappointed. The older Yesterday and younger Today versions of George and Harold travel back in time to find Mr. Krupp. The older George and Harold tried to snap their fingers, but as he had been washing his face, he can not turn into Captain Underpants, and Mr. Meaner beats them up anyway. Once Mr. Krupp dries his face, they snap their fingers and turn him into Captain Underpants, defeating Mr. Meaner and sending him to prison.

After eating an egg salad sandwich with pickle relish and radioactive, Meaner turns into a gigantic blob (because the egg salad contains mayonnaise and he added pickle relish; this would create Zygo-Gogozizzle 24) called Sir Stinks-A-Lot. He then causes havoc downtown. Captain Underpants returns to fight him back, but when Old George and Old Harold are captured and absorbed, Sir Stinks-A-Lot discovers Captain Underpants' weakness and turns him back into Mr. Krupp by splashing water from Franz Pond on him, making him fall down (he's still unharmed because of his superpowers). He then drains Captain Underpants' powers with his own after scanning his DNA, presumably taking the effects of the 3d Hypno Ring as well. He runs off screaming as Old George and Harold telepathically call for Tony, Orlando, and Dawn, Sulu and Crackers' children. They feed him Mentos, Diet Coke, and Pop Rocks, making him explode. Luckily, the three hamsterdactyls and Old George and Old Harold are unharmed, as well as Mr. Meaner, who's back to normal.

Things are back to the way they were, and as young Today George and Harold return their older Yesterday counterparts to their own time, they find that Mr. Krupp doesn't turn into Captain Underpants at the snap of a finger, because Mr. Meaner erased Captain Underpants from existence. Aside from Harold's initial confusion; he, George, and their older counterparts do not seem to care in the slightest. They decide, given there are a George and Harold to cover for them, they'll use Melvin's time machine to find their pets Crackers and Sulu. The younger Yesterday George and Yesterday Harold wake up to find that Tony, Orlando, Dawn, George, and Harold are gone. They go back to their treehouse. Yesterday Harold feels that he and Yesterday George should make another Captain Underpants comic book, but Yesterday George decides that they should scrap the “Captain Underpants” comics entirely and do a comic book featuring Dog Man instead, leading to their future selves encountered by Today George and Today Harold. The book and series ends here, and unlike other Captain Underpants adventures, George and Harold don't deliver their signature lines of "Oh, no!" and "Here we go again!".

• George Beard and Harold Hutchins – Two mischievous best friends who are fourth-graders at Jerome Horwitz Elementary School.
• Yesterday George and Yesterday Harold – George and Harold's doubles.
• Old George and Old Harold – Yesterday George and Yesterday Harold's future counterparts.
• Mr. Krupp – George and Harold's principal. Principal of Jerome Horwitz elementary school.
• Captain Underpants – Mr. Krupp's superhero counterpart. He is later erased from existence.
• Mr. Meaner / Sir Stinks-A-Lot – George and Harold's mean gym teacher who is the main antagonist of this book.
• Tony, Orlando, and Dawn – Three super hamsterdactyls and the offspring of Sulu and Crackers.
• Melvin Sneedly – George and Harold's nemesis.
• Ms. Ribble – George and Harold's English teacher.
• Miss Anthrope – The secretary of Jerome Horwitz Elementary School.
• Miss Calculator – George and Harold's math teacher.
• Mr. Rected – The school guidance counselor.
• Mr. Rustworthy – The school's music teacher.
• Miss Labler – The school psychologist.
• Ms. Guided – A teacher.
• Miss Fitt – Another teacher.
• Ms. Zurry - Another teacher.
• Ms. Dayken – Another teacher.
• Warden Gordon Bordon Schmorden – The jailer of Piqua State Penitentiary.
• Mrs. Beard – George's future wife, who is white.
• Billy – Harold's future husband.
• Meena and Nik, Yesterday George's future children who are biracial.
• Owen and Kei, Yesterday Harold's future children who are adopted.

In October 2015, the book received mass controversy due to Yesterday Harold being gay. Some elementary schools banned the book for this reason. [3][4]

• Dav Pilkey's website
• Trailer at Scholastic's website