In the apartment’s kitchenette, Mario is in the middle of cooking some of his prize winning spaghetti sauce; after pouring some spice into the sauce, Mario proceeds to bring the pot of it over to Luigi, who is working on some sort of device with a screwdriver on the dinner table. As Luigi works, Mario begins trying to convince him to try his spaghetti sauce, which Luigi is hesitant to try at first, being very busy. Eventually, Mario manages to convince an somewhat annoyed Luigi to try a spoon-sized portion of his spaghetti sauce. Tasting the spaghetti sauce, Luigi exclaims to Mario that it is the best spaghetti sauce he’s ever tasted.
After Luigi says this, Mario, proud, says that the taste is caused by his secret ingredient, seeds; unimpressed by this, Luigi is told by Mario that he didn’t use just any seeds, he used dehydrated vegetable seeds. After Mario says this, Luigi responds by saying that, regardless of whether the spaghetti sauce has seeds in it or not, it’s the best spaghetti sauce he’s ever had. Its only when Luigi says this that Mario notices that Luigi has suddenly grown a small patch of leaves on his chest and neck. At first, Mario tries to stay calm and convince a still oblivious Luigi that there is nothing wrong with him. After Mario mentions that nothing is wrong with his neck, Luigi becomes suspicious and runs to a nearby mirror, where he sees the patch of flora that has grown on him. As Luigi panics, Mario tries to reassure him, by saying that at least the color of the leaves that have grown on him match the color of his overalls; unsurprisingly, this fails to calm Luigi, he can only point to his neck and mumble, dumbstruck.
As Luigi stares blankly into a mirror, several vegetable having sprouted from his body, Mario paces back and forth repeatedly. Suddenly, the doorbell rings and Mario rushes over to answer the door. Opening the door, Mario is met by a boy who says he called his farm, to which Mario says yes to, but cites he called Old McDonald’s farm; the boy states that he knows and goes on to say he is Old McDonald’s son, Young McDonald, who was sent to Mario Brothers Plumbing in place of his father, who is at a ‘tater convention.
Leading Young McDonald into the apartment, Mario hears him say that the place smells like a produce section. Leading Young McDonald to Luigi, Mario watches as Young McDonald inspects Luigi and the vegetables growing from him. Dumbfounded by Luigi’s condition, Young McDonald asks Mario if he has tried picking the vegetables to which Mario says no to, saying the vegetables didn’t look ripe. Ignoring this response, Young McDonald asks Mario if he has a pair of clippers, which Mario does have and gives to Young McDonald. Using these clippers, Young McDonald begins to cut vegetables off Luigi, and pulls several off him as well.
With Luigi seemingly cured of his condition, Mario asks Young McDonald to take a look at the sick carrots in the nearby tub garden, which Young McDonald agrees to do. As Young McDonald and Mario look at these carrots, which have begun to shriek, Luigi notices that he has sprouted more vegetables and alerts Young McDonald and Mario to this fact. Seeing Luigi, Young McDonald nonchalantly tells him that maybe he’ll get used to growing vegetables from his body.
Later, as Young McDonald looks through a book, Luigi asks him if he’s found anything, to which Young McDonald replies to with a no, saying that this is a difficult case. As Young McDonald continues to read, Luigi begins to argue with Mario, saying he can’t believe he allowed Mario to convince him to eat his stupid spaghetti sauce. As Mario and Luigi argue, Young McDonald calms them down and tells them that he thinks he may have found a way to help Luigi. Reading from his book, Young McDonald states that Luigi has Veggieitis, a disease that occurs every three-hundred years in only Brooklyn, and only when vegetable seeds are eaten by someone in spaghetti sauce.
Young McDonald proceeds to tell Luigi the only known cure for Veggieitis, eating a rose, which will cause the vegetables on a person’s body to instantly fall off; hearing this, Mario grabs a nearby, rather dead-looking rose and hands it to Luigi, who hesitantly eats it. As Luigi eats this rose though, Young McDonald states that, unfortunately, eating a rose will sometimes cause Roseitis, which lasts for a week, which causes roses to come out of someone’s ears. Glancing at Luigi, Mario and Young McDonald notice that Luigi has sprouted roses from his ears. Telling Luigi to look on the bright side, Mario says that at least with roses coming from his ears, Luigi will smell better.