The episode begins with the Disgustoids celebrating the coming of Uncle Grandpa by partaking in all kinds of weird Christmas-like traditions. When The Fart sees all of this, he tells the rest of the Disgustoids to take down the decorations and proceeds to tell them Uncle Grandpa doesn't actually exist. Festro tells him to sit down and listen to a story so he can become an Uncle Grandpa believer. All the disgustoids sit around Festro as Festro begins to tell them the story of Uncle Grandpa.
Uncle Grandpa begins his day by saying "Good Morning" in the shower. He swiches his head with several different bodies before finding the correct one and going about his daily activities (of course, after greeting Fanny Pack). Fanny Pack asks what Uncle Grandpa has in store for them today. Uncle Grandpa isn't sure so he asks Frankenstein, who in turn responds with a grunt. Uncle Grandpa passes him off as crazy shortly before crashing into someone's backyard.
The backyard actually belonged to Remo and his family. Remo's Dad greeted Uncle Grandpa warmly and explained that he was having a birthday party for his son, Remo. Remo complains that the party is too lame and he wants it to be over. Uncle Grandpa seems excited over Remo's birthday cake before explaining to Remo who he is. Remo is still a bit confused, so Remo's Dad further explains for him. Uncle Grandpa agrees with his explanation as he eats the whole cake and the table. Kev, who is attending Remo's party, seems impressed with Uncle Grandpa's eating habits.
Remo, however, was not impressed. Remo angrily told his dad that Uncle Grandpa was helping to further ruin his birthday party. Remo gets fed up, so he invited Kev and the nameless Red Haired Kid up to his room to break things. Remo's Dad feels ashamed of himself and wishes he could make his son happy. Uncle Grandpa presents him with a solution that will make him very cool. He gives Remo's Dad a pair of shades to make him super cool and look like Rip Dickleson. Uncle Grandpa is about to explain what not to do while wearing cool dude shades, but before he could say anything it was too late. Remo's Dad shade tipped his glasses and ended up becoming a giant lizard man with Rip Dickleson's head. He immediately went into Remo's room and kidnapped his friends.
Remo's first reaction is to call the police, but Uncle Grandpa stops him. He explains to Remo that Uncle Grandpa could get into alot of trouble if the cops get involved, so has him call Uncle Grandpa instead. Uncle Grandpa explains to Remo what happened to his father and informs him that his father is now on Mars with his friends. He sits with Remo on top of Giant Realistic Flying Tiger and brings them up to Mars.
Gweelok interrupts Festro's story to tell him that he needs to use the restroom and to not continue the story until he gets back. Festro waits til he is gone and continues the story anyways.
When they land on Mars, they find a house with a large "Party" banner on it. They decide to check in there for Remo's Dad and friends and sure enough they are in the house. Remo's friends are in a large pot of boiling liquid as the father is preparing them to be eaten. Uncle Grandpa fishes his friends out while the father is distracted and has them all get back onto Giant Realistic Flying Tiger.
Remo reminds Uncle Grandpa that he wants to save his dad because he still cares about his dad even though he is lame. Uncle Grandpa has Remo and his friends go back into the house. Uncle Grandpa then proceeds to engage in an epic battle with Remo's Dad. Remo's Dad ends up eating Uncle Grandpa, so Remo and his friends decide to go break his shades themselves. Once they successfully break the shades, Remo's Dad returns to normal. After being reunited with his father, Remo's dad apologizes for being too lame and promises Remo that he will be cooler next time. Remo's dad then vomits out Uncle Grandpa before Remo explains what happened and how much he enjoyed the whole adventure. Remo's dad blamed the shades for turning him into a monster, but Uncle Grandpa explained they were only a normal pair of shades so he must of had that cool Rip Dickleson cool guy in him the whole time. Remo seemed thoroughly impressed with that fact. When he went to go ask Uncle Grandpa to take them back to Earth, Uncle Grandpa had already left them stranded on Mars. Remo's dad was a bit worried about being stranded, but Remo reassured him that living on Mars is something he's always wanted. Uncle Grandpa rides his magical motorbike into the sun shouting "Good Morning!"
Festro concludes the story, but The Fart was not buying it. The Fart still did not believe in Uncle Grandpa. He leaves to go work out, leaving the rest of the Disgustoids to go do whatever. The other Disgustoids decide to have a turkey drumstick sword fight. While The Fart works out, Uncle Grandpa comes up next to him and begins to work out too. He greets Fart with a "Good Morning" which thoroughly shocks The Fart and the episode ends.