"Oh, Brother!" is the eleventh episode of The Adventures of Super Mario Bros. 3. It aired alongside another episode of The Adventures of Super Mario Bros. 3 entitled "Misadventure of Mighty Plumber" on October 13, 1990.
A rainstorm is taking place in the Mushroom Kingdom one night, and everyone is confined to their homes. Princess Toadstool, Toad, Mario, and Luigi are all inside Toad's house, where the Princess comments that it has been raining non-stop for two weeks while looking out the window.
Toad remarks that the storm going on outside is nothing compared to the one going on inside, and directs her to the Mario Bros. Luigi is trying to read a book, but he is unable to concentrate due to the music that Mario is dancing to. Luigi tells Mario to turn his record down, but Mario does not comply, saying it is hot. Fed up with Mario's music, Luigi pulls the record right out of the player and throws it into the fireplace, melting it. Then he sarcastically replies that "now it's even hotter".
Mario then yells at Luigi for burning his favorite record. Luigi responds by stating that he is making up for the time that Mario busted his favorite wrench. Luigi then pulls down Mario's hat and tugs his overall straps and mustache, aggravating his brother. Princess Toadstool and Toad try to calm them down, but Mario and Luigi ignore them, and beat each other up.
Mario exclaims he wishes that he did not even have a brother, and Luigi, in response, says that Mario can consider himself "debrotherized" as he walks outside, bidding his "ex-brother" farewell. Princess Toadstool tells Luigi to take a Frog Suit for the rain, but Luigi refuses to take one, and walks off. When Princess Toadstool mentions that someone should go after Luigi, Mario agrees and goes, despite the fight he just had. Princess Toadstool tells Mario to take a Frog Suit as well, but he too declines the suggestion.
Meanwhile, Kooky von Koopa is giving King Koopa an explanation of his new invention: The Power Shower. The Power Shower forces rain down upon the Mushroom Kingdom, where it falls through a Warp Pipe into the Pipe World, flushing all the loose Gold Coins through the pipes and into a basin in an underground dungeon. However, a pipe in the dungeon that's connected to the Power Shower bursts, and water starts flooding the dungeon. When Kooky explains that he is unable to fix a leaking pipe, Koopa sends for either of the Mario Bros.
Back in the Mushroom Kingdom, Mario catches up with Luigi, but the two brothers are still mad at each other. Luigi pulls on Mario's hat, overalls and mustache again, and Mario tells him to cut it out. Unknown to them, Kooky is spying on them from the dungeon through his Koopascope. Kooky asks King Koopa which Mario brother they should "Koopnap", and Koopa resorts to a game of eenie-meenie-miney-mo with Mario and Luigi's pictures on dartboards, ultimately picking Mario.
Kooky announces that he will catch Mario with his Plumber Pole, and casts the pole up the pipe that the Koopascope was in. The end of the line comes out of the pipe near Mario and Luigi, and hooks Mario by his overall strap. Pulling back on the Plumber Pole, Kooky pulls Mario back through the pipe, through the Pipe World, and into the dungeon, where a pair of Hammer Bros. apprehend him.
After being tied up, Mario tells King Koopa that he will never fix his plumbing, but Kooky explains to Mario that they have the power to make him do whatever they want with his latest invention: The Lame Brainer. Upon placing the Lame Brainer on Mario's head, Mario's mind and voice become drone-like, and he tells the Koopas that he will do anything they say. Kooky puts Mario to the test by offering him a plate of pasta. Although Mario says he loves pasta, Kooky tells him that he actually hates it, and Mario then declines it in disgust. Koopa then has Kooky order Mario to fix the leak.
Meanwhile, Luigi realizes that he must save Mario, and jumps into the Warp Pipe that Mario was pulled through, taking him to a flooded section of the Pipe World, where a Boss Bass chases after him. Luigi returns to Toad's House, and without saying a word to either Princess Toadstool or Toad, puts on a Frog Suit, becoming Frog Luigi. Luigi then returns to the Pipe World.
While swimming through the Pipe World, Frog Luigi easily swims past the Boss Bass that had chased him earlier. A Lava Lotus goes ballistic while attacking Luigi, but Luigi manages to dodge it as well. A Blooper Nanny and her babies come out of a pipe and chase after Luigi as well. Luigi opens up a vault which he enters, and the Bloopers follow him. Luigi quickly swims out of the vault, locks the Bloopers in and continues onwards to rescue Mario.
Back in the dungeon, Mario finishes patching up the leak in the Power Shower pipe, pleasing King Koopa and Kooky. Just as the Koopas rejoice, Luigi comes out of the pipe over the basin that is holding the collected coins. Luigi asks the Koopas what they have done with Mario, and Kooky explains that they have turned him into their slave. With Mario under their control, Koopa orders him to attack his brother. Mario, having no free thought, is forced to obey Koopa's orders, and prepares to smack Luigi with his wrench.
Luigi hops back as Mario attempts to smack him, and tries to tell Mario to come to his senses. Mario does not listen, and tries to hit Luigi, who is too fast for him. Luigi tries to remind Mario of their previous experiences, including their childhoods and many plumbing jobs, as well as the time he lent Mario his screwdriver when Mario lost his own, but nothing works.
Luigi concludes that he needs to try another approach to reach Mario, and does this by pulling on the Lame Brainer, Mario's overalls, and his mustache. Mario tells Luigi that he hates it when he does that, but under his own control. Mario's thoughts overload the Lame Brainer, which goes flying off of his head, and onto Kooky's. With Mario back to normal, Luigi makes up with him. Mario then goes up to Kooky, and with the help of the Lame Brainer, orders him to attack Koopa. Unable to think for himself, Kooky chases after Koopa, who is unable to stop him. As Kooky chases him upstairs, Mario and Luigi congratulate each other.
Back in the Mushroom Kingdom the next day, the rain has finally stopped. At Toad's house, Princess Toadstool thanks Mario and Luigi for dismantling the Power Shower, and for returning the coins to the Pipe World. Luigi then tells Princess Toadstool and Toad that he and Mario will never fight again.
Mario confesses that their argument was all his own fault, but Luigi corrects him, stating that it was his own fault. Mario and Luigi then start fighting with each other again, and Luigi tugs on Mario's hat, overalls and mustache once again. Mario then comments to the audience, "brothers, you can't live with them... you can't live without them".
Animation and continuity errors
Names in other languages