Flu-In-U-Enza is episode 11b of Rocko's Modern Life. It aired on October 10, 1993.
Rocko is laying in bed with Spunky during the night holding two tickets to watch the W.W.W.W.F. Wrestling Main Event. He says that it will be the big day. The next morning, Rocko wakes up with a red nose with an excessive amount of snot running out. He goes to the bathroom to stuff it up with toilet paper. But it only causes the snot to run out through his ears instead. Realizing that he has caught the flu, Rocko leans against the mirror wearily and says that he has to call Heffer, who takes him to the doctor, where the two sit in the waiting room. The bird sitting adjacent to Rocko smokes a cigarette, and as a result coughs his heart out of his mouth and drops dead subsequently. When Rocko walks up to the front desk, he tells the cow nurse if he can see the doctor. The nurse gives him a stack of papers, telling him that filling them out is the prerequisite of seeing the doctor. She also tells him that he should take the east wing to the elevator and take the west wing to the doctor's office (right before hitting on Heffer as well). In Dr. Bendova's office, Rocko looks around to find the unsanitary condition around it. Eventually, the doctor walks in and runs tests on Rocko. Rocko tells him that all he needs is medicine and the doctor gives him a prescription of the medicine. After getting the final test ran on him, Rocko wobbles as he exits the doctor's office.
Back at home, Rocko takes the pill he was instructed to buy and reads a label that says "WARNING! Not to be taken orally." At which point, Rocko begins feeling dizzy and runs into the bathroom, where he pukes in the toilet. While Rocko is laying on the floor, a half-eaten hot dog (named Retch), a slice of cheese (named Hurl), and a half-eaten pizza (named Spew) emerge from the toilet and introduce themselves as "The Enchanted Upchucks," who take Rocko to the kitchen to get him cured. They make toe jam tea, which causes Rocko to fall back in disgust. Spunky hops on the table and drinks the tea from the mug. When Rocko says that he has a headache, Retch opens up his head and finds that his brain is locked in a metal brace. Retch tries to unlock the brain out from the brace, but only ends up squashing it. So he puts it back in Rocko's skull and the wallaby, once again, falls to the floor. The Enchanted Upchucks decide to give Rocko a heavy dose of Vitamin C and iron. So they put a funnel in Rocko's mouth and drop four oranges and a watermelon through the funnel and into his mouth right before dropping an iron on his head. The Enchanted Upchucks decide to put a block of ice on Rocko's head and mix in some pepper, cayenne, Tabasco sauce, and chili sauce in a bowl. Retch uses a syringe to contain the hot liquid with and adds a drop on Rocko's tongue, causing the ice on his head to melt and him to spit out a huge flame of fire, which burns a chair. Rocko is now infuriated and chases the Enchanted Upchucks in the bathroom, where he corners them. When he realizes that he can smell again, he discovers that he has been cured and thanks the Enchanted Upchucks as the trio jump into the toilet. Spunky comes into the bathroom and hops in Rocko's arms. Rocko tells his dog that he is all better and the two can go to the big game tomorrow.
The next day Rocko wakes up fine, only to discover that Spunky has caught his flu. Heffer comes over to see how Rocko is doing and Rocko tells him that Spunky has caught his flu and he will miss the game to stay at home to take care of Spunky. He hands Heffer the tickets and Heffer tells him that he'll have a great time at the game. Rocko and Spunky watch the wrestling match on TV and Dr. Bendova is revealed to be the first wrestler, which prompts the nurse, who Heffer has took along with him to attend the game, to jump into the ring and attack the doctor. When Rocko hears a voice that says "I got twenty on the nurse", he turns to his right to find the Upchucks sitting adjacent to him watching the game as well.
- In the beginning, the tickets add an extra "W" to W.W.W.W.F.
- The Wild World of Wacky Wrestling Federation is a parody of what is now known as Worldwide Wrestling Entertainment, but what was then known as the Worldwide Wrestling Federation.
- The hot dog, cheese, and pizza are named "Retch," "Hurl" and "Spew", all synonyms for throwing up. They are collectively known as the Enchanted Upchucks, another slang term for vomiting.
- In 2020, Nickelodeon banned certain episodes of their shows that featured characters getting sick due to the COVID-19 pandemic. While the season four Rocko's Modern Life episode "Wimp on the Barby"/"Yarnbenders" was pulled because "Yarnbenders" featured Filburt getting sick ("Wimp on the Barby" had no content that would be deemed inappropriate due to the COVID-19 pandemic), this episode surprisingly aired with no problems.
- This is the only episode of the series that has been never aired in Latin America or Spain on Nick because it was censored in the United States, so they never translated it to Spanish. It was later figured out that the did, in fact, dubbed this episode in Latin America when various local channel aired the episode in various Latin America countries. It also aired with Spanish audio on the NickSplat block since January 2019 via SAP.
- This episode also has never been aired in Russia on TNT or Paramount Comedy.
- The baby crying in the background was a sound effect called "Hollywoodedge, Baby Crying Slowly PE144001". Also, the rooster crow from "The Good, The Bad, and The Wallaby" and "Who's For Dinner?" is heard again in this episode.
- This episode shares a similar plot to the SpongeBob SquarePants episode "Suds".
- In the end credits, Linda Wallem is credited for voicing Virginia Wolfe, even though the character was not in this or "Rocko's Happy Sack". Linda was still in this episode though, voicing the cow nurse.
- Rocko saying "What the?" has become an Internet meme.
- The funny eye exam chart makes a visual appearance, "I am a prisoner in the crazy doc's broom closet". The other time the funny eye exam chart appeared was in "Skid Marks", where Rocko reads it aloud.