Flappy Bob is a clown who was separated from his clown parents as an infant and was found by Sanderson and H.P as they were driving back to Pixie World after another failed thirty-seven year plan attempt to take over Earth and Fairy World. When they found him, they attempted to use him for their new thirty-seven year plan.
Even when he is shown as a baby, Flappy Bob is in clown make up along with his parents. However, after being turned into a cold boring businessman by the Pixies, Flappy wore no make up and appeared as a plain looking man with a business suit. After he learned the true meaning of fun, Flappy Bob put his clown make-up and clothes back on.
After being found by the Pixies, thirty-seven years went by and Flappy Bob became a greedy, boring business man taught to think that fun was boring and that boring was fun and no longer was the clown he once was. Eventually creating Camp Learn-A-Torium after the Pixies leave some blueprints on his briefcase after graduating law school. Then, shortly after Timmy made his wish that kids could take over the Earth it wasn't long before he learned that his camp was torn apart. Completely outraged, he signed a contract with H.P. and Sanderson to make the world boring and dull which he was described as fun, but it wasn't long until he overheard them of everything he originally thought though he learned that they were using him all along this entire time. So he returned to being a fun-loving clown and showed Timmy a loophole in the contract. He then helped Timmy put fun back on Earth which eventually got HP and Sanderson's attention.
Flappy Bob then notes that they lied to him about everything he originally thought was fun and were just merely using him. HP and Sanderson note that is true, but they still have the iron-clad contract Flappy signed. Flappy notes it is true that everything in the contract is binding, and that is why he wants to turn the Pixies' attention to some small print. It turns out that the contract says that Earth will be safe and fun as defined by Flappy himself and Flappy reveals that he defines fun as everything that is fun is supposed to be.
Timmy then notes to the defeated Pixies that they shouldn't have sent him to law school. After telling Timmy that he will pay next time, HP then tears up the contract and restores Fairy World and Earth to how it was before. And with the help of Timmy, Cosmo and Wanda, he found his clown parents, disowned Camp Learn-a-Torium, and learned the true meaning of fun. Flappy Bob is no longer considered a villain, although he has not made a single appearance after his last so there is no way to be sure.
His name and his clown appearance are possibly homages to The Simpsons characters, Sideshow Bob and Krusty the Clown.
He had a button on his desk with a trapdoor, which indicates that Happy Peppy Gary and Betty get on his nerves pretty often (when they tried to do their trademark song he yelled out "Not now!" and got rid of them with the trapdoor).