Festro reads a story about Uncle Grandpa to Fart to make him believe in Uncle Grandpa. The story shows Uncle Grandpa trying to make a kid named Remo have a great birthday. However, he ends up turning Remo's father into a giant lizard monster who takes Remo's friends to Mars where they must be saved. In the end, Uncle Grandpa leaves Remo and his Dad on Mars, which Remo seems to enjoy. In the end, Fart still doesn't believe in Uncle Grandpa until Uncle Grandpa comes into Farts room and says Good Morning to him.
It starts with all the disgustoids from Secret Mountain Fort Awesome aside from The Fart celebrating Uncle Grandpa. The Fart doubts their beliefs in Uncle Grandpa and tries to get them to clean up the mess, but Festro insists there is an Uncle Grandpa and decides to read The Fart and the rest of the gang a story. It then starts with Uncle Grandpa waking up and getting himself ready. Once he's ready he begins to drive the RV and asks Frankenstein if they have anything planned for the day. The RV crashes and Uncle Grandpa winds up in Remo's backyard. Uncle Grandpa of course crashed into everything at his party and destroyed it, so Remo was unimpressed and believed the party was lame. Instead, he invited his friends up to his room to go destroy stuff. Remo's Dad was upset that he wasn't cool enough to throw a good birthday party for him. Uncle Grandpa gave him some shades that would help him become cool. It certainly did turn him "cool", it made him look like a celebrity. Uncle Grandpa tried to warn him about what not to do in the shades. Before Uncle Grandpa could warn him about shade-tipping, Remo's Dad did it and turned into a lizard monster. The lizard monster broke into Remo's room and kindapped Remo's friends. Uncle Grandpa and Remo set out on an adventure to save Remo's friends and return Remo's Dad back to normal. After epic fight scenes and silly shenanigans, they were able to save Remo's friends AND dad. Remo's Dad thought he permanently ruined Remo's birthday, but after all the shenanigans and epic battles, Remo was thoroughly impressed and thought his dad was cool. Uncle Grandpa drove off without them, leaving them stranded on Mars forever, but they didn't mind since Remo always wanted to live on Mars. After Festro read the story, The Fart thought it was absolutely ridiculous and when to go about his "reality" activities. During his reality activity, Uncle Grandpa snuck through the window and greeted The Fart. The Fart was stunned and fell over from shock.