Mario goes on a adventure after going off course but he usually does anyway...
Mario starts at a race in Royal Raceway, but is much higher than the other racers. Once the race starts, Mario shoots infinite shells at everybody, causing them pain and damage. They speed ahead after this, leaving Mario alone and sad. He tries to find enjoyment in the crowd, but they boo him because of his hacks, and cheer the other racers. He droves on them and launches shells at them, but after a while, just drives off, scared.
He continues to race, getting hit by his own shells when he launches them at one point. He sees a ledge and wants to go over. He falls into the water however, being too heavy for the cheat to work.
The water leads him through the sewers to the jungle. He sees a boat and yells at the DJ to play loud music so the attention of the boat is obtained. He plays Justin Beiber's "Baby" song, which angers Mario because he wanted to get them closer, not farther. Mario asks if the DJ has any good music, who replies with a cricket sound, indicating he doesn't. Mario then tries to jump over. He makes it, but the boat kills him, and Mario declares it "a lie." He tries 3 times to jump to it, failing each time. He tries to find another way out of the jungle, Lakitu telling him to stop, which Mario yells at him for. He levitates somewhere to find there is no bridge where there is supposed to be one. He ends up falling and is saved by Lakitu. He falls in the jungle waterways and ends up at a beach.
Mario passes the finish line's 2nd lap, which Mario doesn't understand, and decides to levitate into the blue-green sky, but ends up on the rock, tumbling. Hours pass and Mario is lifted onto the beach, Mario thinking "God is jealous." He drives for a bit and tries to find a way out. He levitates for a bit, and lands at a wooden road.
He drives for a bit, Lakitu flashing the 2nd lap at him again, Mario is not pleased at him. Mario remembers something about him killing Luigi and stuffing his body somewhere. He tries to say hello to the fish but fails, and notices the Boos as debris. He notices the building as like his house, except that it's lacking "the dead bodies." He later tries to levitate out, landing at a circuit.
He wonders whose this is, but doesn't seem to care too much and gloats about himself while driving. He drives for a bit, and notices that Luigi owns this course. He wants to own it, and tells Lakitu this, who tells him he owns another circuit. He sees a "lollipop" and goes up to it but it turns out to be fake as Lakitu encounters him as Mario is commenting on Lakitu's taste. He levitates out, landing in a desert.
As he drives, the engine breaks down and lands in front of the train. It blows up as Mario is tossed up. Somehow it starts working again just as Mario drives after the train, with passengers wondering who Mario is. As they start insulting Mario, which he hears, he rams into them, causing them all to die. He later ends up on a highway. He wishes to get back to the castle, and wants to know where Toad is. Toad is shown to be sliding down Princess Peach's slide.
Mario continues to drive and levitate, and wonders what Luigi is doing, who is in fact, getting kissed by Peach. Mario decides to levitate out. He lands in an ice world, and ends up under a penguin, as an egg. He is next seen tumbling down, in an area that isn't home.
He lands in a mountainous region, and reads a sign that Mario interprets as that the mountain has eyes. Mario worries if Bowser is sad, when in fact it's the complete opposite, and he's celebrating for that very reason. Mario sings a song, wondering where it came from, and encounters falling coconuts. He wants to eat one, and tries, but gets flattened.
He drives elsewhere, on a farm, and thinks he's lost. He thinks this place reminds him of the time when he hacked Farmville. He drives further and encounters a cow, and gets scared when all he sees is the cows bottom when he gets close to it. He encounters another cow, and calls them cardboard cows.
He ends up at Rainbow Road, Mario judging it the "hippie road," and finds the faces again. He sees "Pac-man" (an angry Chain Chomp) and chases after it after it hits him. He aims himself at it, but ends up in the air. Lakitu tells him this is why he never lets Mario have a gun.
Mario falls from the sky, through the flagpole, and dies.
Later, Mario tells Toad that it ended well, Toad telling him it's better when he's not there. Mario asks the viewers if he's cool, and Lakitu replies that only if Mario is hurt.
Later, Mario is shown trampling supposed viewers that don't like this video with his kart.