Short Story is episode 13a of Season 2 of the series
Feeling self conscious due to a short height, Really Really Big Man gives Rocko a "vertical boost".
A giant heart is attacking the city (thus a giant heart attack) and is about to devour to swine citizens until Really Really Big Man shows up and clogs up the heart's arteries with the pigs, killing him. The two pigs congratulate Really Really Big Man and the superhero flies away. The events during the beginning is revealed to be from a comic book that Rocko is reading, and Rocko feels the advantages of being big. An alligator shows up and asks Rocko for a copy of the Yellow Frog comic book on the top shelf. Rocko climbs on top of the shelf and the frog on the cover of the comic book comes to life and grabs Rocko's arm. The wallaby is sent tumbling down the floor and hands the alligator the Yellow Frog comic book. But the alligator changes his mind and takes Rocko's box (which he uses to stand due to his short stature) instead and leaves. Later, a group of sorcerers come over for a copy of the comic book Snow Bunny and the Seven Short Ears, which Rocko promptly offers them. As they leave, one of the sorcerers tells him "Thanks a lot, pee wee," causing Rocko to feel sensitive over his short height. Three elves come by, but an angry Rocko tells them to get out, refusing to let anyone else mock him for his height (which he claims that he's "vertically challenged"). Mr. Smitty then comes around and leaves, oblivious to the fact that Rocko is standing behind the counter.
Rocko enters his car and discovers that his inflatable booster cushion went flat. He desperately tries to blow it back up, but to no avail. An elephant comes around and blows it up for him successfully. As Rocko continues to drive home, the thoughts of the previous customers mocking his height get into his head. His cushion eventually pops and he loses his ability to see over the windshield. He crashes into the front gate of the zoo and dazes out.
He wakes up to find Spunky licking his face and finds that his car is in the middle of grass. Just then, he hears an earthquake and runs with Spunky in his hands out of the car, which a mysterious foot steps on. It turns out to be the alligator from earlier in the episode and he accuses Rocko for making him step on it. Rocko runs away and bumps into Mr. Smitty, who is revealed to be a centipede. He then notices a pink bubble floating ahead, and the bubble pops, revealing a rat fairy named Tyrone, who is the fairy of Bigland. He tells Rocko that "being big ain't all that's cracked up to be" right before Rocko retorts that "being short's no picnic either." He wishes that he was really big, which Tyrone grants him. Rocko begins to grow, eventually becoming as big as a skyscraper. He puts Spunky inside his shirt pocket and takes a whiff of the fresh air, which causes a flying airplane to jam inside his nose. Rocko pulls out the airplane and tosses it back into the air. Rocko feels great about his size and walks to O-Town. As he bends down to view the train, the citizens call Really Really Big Man to inform him of the giant wallaby. He confronts Rocko, who doesn't notice Spunky falling out of his shirt pocket and into a sewer. When the wallaby turns around, he accidentally destroys a building adjacent to him with a Godzilla-style tail swish and tries to put it back together, only for it to break even more. Really Really Big Man punches Rocko in the face, which sends him flying into the ground, causing numerous buildings to fall on top of him. Rocko tells the superhero that he is not a monster and only wanted to be big. Really Really Big Man then recognizes Rocko from working at the comic store and reminds him of how he once saved Heffer from choking on a chicken bone (To Heck and Back), the foul ball he gave the kid at a baseball game (Spitballs), and took his appendix for a roller coaster ride (Tickled Pinky). The superhero tells Rocko that generosity and kindness really makes a big man. Before he leaves, he reminds Rocko that Spunky is inside a sewer, much to Rocko's horror. He shoves the building off of him and walks to the sewer to save Spunky, but his hand is too big to fit through it. Tyrone the fairy reappears and offers Rocko a pair of red mittens to clap and say "I wish I was small" three times. Rocko does this and reverts to his short size again. He falls into the sewer and rescues Spunky, only to get sucked down the drain with his dog.
Rocko then wakes up to find himself lying in his bed and Spunky licking him in the face. He realizes that he had been dreaming all along. He then see Really Really Big Man, the alligator (who offers him his box back in deference to Really Really Big Man), Mr. Smitty, and Joe Murray (who tells him that he is off-model). Really Really Big Man says that "you don't have to be tall to be really, really big" right before he flies away.