A strange man who is the uncle and grandfather of everyone in the world must do battle with a gang of mutants, after an attempt to gain the appreciation and love of a nerdy teenager goes awry.
When Gweelok builds a teleport-a-potty, Festro and the monsters search for a place where pizza grows on trees. But when Festro went to go "boom boom" and flushed the teleport-a-potty, the monsters got stuck in another universe.
The Disgustoids disguise themselves as cops so they can walk on the surface, but whilst Fart wants to follow the duties of a cop, all Festro, Gweelok, Dingle, and Slog want to do is pump up the jams.
The Disgustoids are delighted when Secret Mountain Fort Awesome comes to life and starts wrecking havok on the surface world, but when Fort falls in love with a another mountain, Festro tries to break up the relationship.
The monsters bet Gweelok that if he used the Internet within 24 hours, he would have to stop using it at all times so he can hang out with them forever and ever.
Gweelok invents a special sauce to help Festro get rid of his nightmares, but after Festro overdoses on the batch, it causes his bad dreams to run amok in the real world.
When Festro's nephews visit to be babysitted, they turn out to be complete wimps. The gang teaches them how to be "rude dudes with atitude".
After giving all the gang's money to a prince from Nawibawabi, Gweelok needs to find money to pay the fort rent. The Disgustoids try to find a new roommate, but it turns out that she is the prince from Nawibawabi.
The bros make many Fart clones after looking through his secret diary, so they try to get rid of them before the real Fart finds out.
When Gweelok Breaks Fart's chair, The disgustoids blame it on Festro. But it was really gweelok who did it.
The Disgustoids discover that their newly repaired Megavision has the ability to see into the future.
Every time the Disgustoids have a party, Slog turns into "Party Slog" which annoys the bros, but when trouble strikes they need him to do so.
The Disgustoids go on a road trip.
When Dingle abandons his friends they try to get him to come home.
When Festro finds out about a place called "Colonel Monster's Monster Time Pizza Palace" he goes there only to get trapped by the people who go there.
The Fart is elected as the Disgustoids' new leader when everyone tires of being bossed around by Festro.
Uncle Grandpa shows up at a lame birthday party and tries to make it cool.
Festro gets glasses so he can look smarter, but he thinks wearing glasses means "smort".
Festro experiences a personality change after getting an aching tooth pulled out.