The plot starts out in Peach's Castle laboratory, where Mario has successfully made a Mushroom and is relieved after all those failed attempts (which were Mario blowing up a mushroom, then making it come alive, causing him to shoot it, and then turning it into a Toad).
Mario puts the mushroom into the plate of spaghetti, making GOLDEN SPAGHETTI!! Mario s**ts his pants due to shock. Luigi comes into the laboratory asking Mario what he just made, to which Mario replies "The Irresistible Golden Spaghetti"
Suddenly, the castle starts to shake, and as Mario and Luigi go outside to find the source, the screen cracks and Mario Head (also known as The Giant Floating Mario's ugly Head) that appears in mario teaches typing 2. Mario and Luigi scream in horror and run to Bob-omb Battlefield, hoping to lose it, but Mario Head follows them there. Mario Head comments on the nice golden spaghetti Mario had just made, and asks if he can have it, to which Mario angrily replies "NO!"
Then Mario Head becomes angry and the Old Man Hobo appears saying, "Nice Job, Dickface!" Mario Head sucks everything into his mouth, including Mario, Luigi, Chain Chomp, and the entire battlefield.The title then appears on a black screen. At the same time, a burp is heard in the background and the Mario Head is asking, "Hey where did everybody go?"
Some guy asks Daisy if she really is a girl. Daisy says yes and the guy shouts MARRY ME!!!!!!!!!!!!.
A Goomba says to the viewers that sometimes he likes to go under his bed and pretend he's a carrot.
Mario is about to fight with Darth Vader, who then says he's his papa. They argue until Darth Vader cuts Mario's hand off.
Mario is about to answer a Pokémon question, and the guy who was playing the game says it's Pikachu. However, it isn't Pikachu and instead another Pokémon named Clefairy, making the guy ragequit.
Pete the Piranha's best friend Jimmy asks him where they want to go. Pete, however, sees Jimmy doesn't notice that Pete is dying of dehydration and responds by shouting to "GIVE ME SOME F*CKING WATER!"
SMG69 begs SMG4 to appear in a video, which the latter disproves. Despite this, SMG69 keeps begging, him, causing SMG4 to ultimately kill him by throwing him into the Sun then a message appears saying DON'T BE A TOAD.
Mario tells Luigi that he looks like sh*t, which makes him get his revenge by being on TV while doing his Death Stare and flipping off Mario.
Some guy at the Snow Mountain sings ""What's This?" from The Nightmare Before Christmas. But only to got ran over by a giant snowball making him to shout "WHAT THE F*CK!?".
Boy and Gurl make out, but then Gurl asks Boy to love her 4ever. Boy declines, causing her to cry and got ran over by Finn's go-kart. Boy was crying and went to her corpse, whispering to her that he meant he will love her...'5ever'. The Narrator then starts to cry hysterically and a message appears saying "lik if u cri evertim. ;_;"
Po falls out of bed one day. She keeps falling over and out until she falls over from a surprise. The rest of the Teletubbies then fall over one by one, followed by a message that says Don't do drugs or you'll trippin ballz.
Justin Bieber sings "Baby", only to be interrupted by Mario and Luigi (wath a gay skin).
Tinky Winky is spinning on the ground while imitating a chainsaw (in Homer Simpson's voice).
Wario told Waluigi to stop watching Super Mario Land 2: 6 Golden Coins commercial video. However, this backfires as Waluigi goes insane, running out on the street, shaking X violently, and causing a car to crash.
Bowser and MarioMario54321 prepare to duel. But first, Bowser say "but first, lemme take a selfie" and starts dancing to the song leaving MarioMario54321 to stare with a shocked face.
Mario and Po are dancing to "Slap that A$$." Then the red plumber is seen naked and showing his a$$ to Toad. After that, Dr. Eggman is shown slapping Dumbledore's butt and running off laughing like Peter Griffin while Dumbledore said "HEY, WHUT DUH FUQ?".
It turns out that it was all a dream that Mario had while inside the Mario Head. He wakes up in a space scene, startled. Luigi reminds him that he was only dreaming and that they were still stuck inside the Mario Head, to which Mario once again denies it's his head, calling it ugly. The Mario Head burps and says, "Hey, that was pretty good."
As Mario fears death, Luigi blames him and his golden spaghetti, giving Mario the idea of finding it. Luigi fears that the world is already destroyed, but in fact, it's still there. A quick glimpse of Peach's Castle is shown with the Mario Head spinning in front of the castle. Someone random person sees it and runs away, horrified. Mario finds the golden spaghetti and asks for its help, only for it to ask for the magic word.
Just as Mario and Luigi lose hope, Toad appears telling the duo that he knows a way to get out. He yells at the Mario Head, telling it that he pooped in his mouth when it swallowed him. Then the camera zooms out of Mario Head's insides, and then the mortified Mario Head expels everything out, including, Mario, Luigi, and Toad. As the Mario Head threatens to kill Mario, Mario makes it swallow a bomb and the Mario Head says "Hey, that was pretty good," before exploding.
SMG4 arrives, asking them "What have you guys done to this place?" He then finds Mario's golden spaghetti and eats it. SMG4 flies out into the horizon, naked, and collides with the Old Man in a bathtub, causing an explosion while Wario appears on the side screaming. Satisfied, Mario and Luigi share a high five as the episode ends.
In the Teletubbies scene, when Po fell from the chair near the table, and the Teletubbies said "Uh-oh," there were two Laa-Laas instead of Dipsy and Laa-Laa.
The scene with SMG4 killing SMG69 (Toad) by throwing him into the Sun might be a reference to a scene of the video "R64: Mario Simulator" where Mario, as Super Saiyan Mario threw the cartridge of the video game Mario Simulator into the Sun, which itself was a reference to the AVGN video Superman 64, where the Nerd throws the Superman 64 cartridge at the sun in the same fashion.
The scene with the Goomba saying he sometimes likes to go under his bed and pretend he's a carrot may be a reference to a skit in the episode "Ssenmodnar 3 (10,000 subs special)" where SMG4 says "Sometimes that night I like to go under my bed and think I'm a cat".
This is the first time where SMG4 eats spaghetti. He's known to hate that dish (and italian food).
SMG4 was just really hungry, so he ate the spaghetti.