While sitting in detention, George and Harold accidentally create an army of evil talking toilets, and Principal Krupp's alter ego, Captain Underpants, has to save the world from it.

After being sent to jail for the rest of their lives, George and Harold are taken on a trip back in time by Tippy Tinkletrousers back to their Kindergarten days where they must deal with their bully without the help of Captain Underpants.

George and Harold are usually responsible kids -- whenever anything bad happens, George and Harold are usually responsible! This time, they accidentally invent an army of terrifying talking toilets. Luckily, they know a superhero with enough snap in his waistband to save the day! This looks like another job for the amazing Captain Underpants!

George and Harold have played a trick or two on nearly everyone at Jerome Horwitz Elementary. When their latest prank causes the school's cranky cafeteria ladies to quit, Mr. Krupp hires a trio of unusual replacements - who happen to look an awful lot like aliens! Will that curtain-caped crusader, Captain Underpants, save the day once more? Or will those outer-space cafeteria ladies have him for lunch?

George and Harold are always good at using their imaginations, and that drives their mean homeroom teacher, Ms. Ribble, crazy! But this time, they've come up with much more than a silly prank...With her horrendous hairdo and two rabid robots, Wedgie Woman is well on her way to world domination, and only the Waistband Warrior can stop her!

George and Harold are a couple of class clowns. The only thing they enjoy more than playing practical jokes is creating their own comic books. And together they've created the greatest superhero in the history of their elementary school: Captain Underpants! His true identity is SO secret, even HE doesn't know who he is!

George and Harold thought they were beyond boogers. Their new pet, Sulu the Bionic Hamster, had defeated the Bionic Booger Boy, and through the wonders of science, Melvin Sneedly had been brought back to normal (well, almost normal). It looked like their last adventure was actually going to have a happy ending... except for one thing (well, three things) -- the Ridiculous Robo-Boogers. Now George, Harold, and their buddies are on the run -- with the...

The teachers are nice, the cafeteria serves delicious food, and the school principal, Mr. Krupp, thinks George and Harold are hilarious. Something is very, very wrong - and it gets even wronger when the boys' pet pterodactyl, Crackers, and Sulu the Bionic Hamster are captured by George and Harold's evil-twin look-alikes. Now George and Harold must face their greatest foes yet: THEMSELVES! Can they handle this mess on their own, or will they need Captain...

George and Harold, and their doubles, Yesterday George and Yesterday Harold, have a good thing going. Two of them go to school, while the other two hide in the tree house and play video games all day -- then they switch! But it turns out there's something rotten in the state of Ohio, and it's smellier than a pile of putrid gym socks. The boys' malicious gym teacher, Mr. Meaner, has created a method of mind control that transforms their fellow students...

The monstrous Turbo Toilet 2000 is determined to take revenge on George, Harold, and Captain Underpants.