Rocko's Happy Vermin is episode 6b of season 3 of Rocko's Modern Life.
The bugs are trapped in Ed Bighead's prison box and are eventually grabbed by Ed himself. He drops them on his peanut butter-spreaded bread, but Flecko grabs onto his finger. So Ed puts the fly into a bottle of grape soda and devours the rest of the bugs stuck to his peanut butter toast. He grabs the bottle of soda and drinks it empty. Luckily for Flecko, he grabs Ed's uvula and bites it right before he escapes from the toad's mouth. The elusive fly ends up inside the drain of the sink and Ed sticks his tongue inside, attempting to catch him. Flecko turns on a switch in the drain, activating the garbage disposal as Ed's tongue ends up getting shredded.
Flecko orients through the pipes and ends up in Rocko's kitchen sink. When he views Rocko walking inside the kitchen, the wallaby squelches himself from stepping on a bug crawling on his kitchen floor and lets it crawl. Flecko then hatches an idea and frees the flies from Ed's prison box.
Back at Rocko's house, Rocko walks into his kitchen to find a prolific number of bugs inside his kitchen. Rocko tells the bugs to leave. But they don't take him seriously and laugh at him. Rocko gets Spunky to order them out, but one of the bugs scares him off. So Rocko suggests the bugs to take a vacation at a nice place.
Meanwhile, Ed is enjoying his breakfast and notices that the bugs are all gone. Back at Rocko's house, Rocko calls an exterminator to get rid of the bugs out of his house. But quickly takes it back when the exterminator tells him that he will kill them, as Rocko never intended to hurt the bugs. Later, Ed comes over Rocko's house to ask him if he wanted a cup of butter and discovers the bugs inside the kitchen. He tells Rocko that he can get rid of them for him, saying that he'll send them to camp, and enters the kitchen to capture them. When the flies disperse to hide, Ed successfully catches them via vacuum cleaner and takes the bag of flies with him home.
Flecko is revealed to be the only bug who hasn't been caught by Ed and is seen hiding inside Rocko's television. He is eventually caught by Rocko, who takes him to the Bigheads' house, thinking that Ed would invite them to camp. Rocko knocks on the door and Bev answers it and lets him walk into the kitchen to give the jar to Ed, who is reading through bug recipes. An annoyed Flecko finally exhales into the glass and writes on it to remind the naive wallaby that Ed is going to eat him and the other bugs, appalling Rocko. So Rocko lets Flecko out of the jar and the fly flies in front of Ed's face, prompting the stubborn toad to flick his tongue at him. He ends up burning his tongue on the stove and grabs a baseball bat to whack Flecko, only for the latter to grab Ed by the lips and putting it over his head. Ed pulls his lips back in place and is subsequently crushed by a piano dropped on top of him by Flecko.
Rocko takes the bag of bugs with him, but is stopped by Bev, who is about to take them to the kitchen. So Rocko decides to stuff the bugs into his mouth, runs to the bathroom of his house, and spits them out in disgust. He rinses out his mouth to efface the horrible aftertaste. Flecko and the other bugs thank Rocko for rescuing them from Ed and take a trip to the Caribbean Island via cruise ship, which they infest.
- Only episode where Flecko is seen wearing red trousers instead of his usual blue.
- This episode is similar to the SpongeBob SquarePants episode Plankton's Army.
- Ed mentions sending the bugs to camp, which foreshadows Joe Murray's following show Camp Lazlo.