SMG4: Little Penguin Lost is the forty-sixth episode of Season 9 and the five hundred and forty-eighth overall to be uploaded by SMG4.
This episode was aired on December 14, 2019.
The episode starts with Mario and Meggy going to Gamestop to buy "Super Woomy Adventures," but due to the holiday season, the store is closed. Mario attempts to break in but fails. When Meggy tells him to leave, Mario agrees, on the condition that Meggy drags him home, to which Meggy abandons him. Mario runs to Meggy but ends up tripping on a baby penguin named Tuxie. Upon seeing this, Meggy suggests they bring it back, but Mario instead knocks it off a cliff, much to Meggy's dismay. Mario however, tells her that he did it numerous times in the past and that Tuxie will be fine. A Mother Penguin sees this, but instead of attacking, takes Meggy away, mistaking her for her child, as well as knock Mario off the cliff after he makes fun of the penguin.
Meggy is stuffed in a penguin suit, and begins to like the penguin experience after being offered McDonald's food, but becomes horrified upon learning she has to eat it like a bird. Mario attempts to get Meggy back by throwing Tuxie in the house and telling the mother that Tuxie's her real son, but the mother throws Tuxie out the window. Then, Mario knocks on the door, to which, when opened, Mario casually asks to steal the mother's child. The mother realizes that he's not the usual guy who steals her child, and Mario rushes in to escape with Meggy. The two come across a giant slope, which Mario rides, using Meggy as a snowboard. They use a Mr. Blizzard to make a huge snowball, which flies into the air via a ramp, thereby finally getting away from the mother.
Upon landing, Meggy is released from the suit, only for her and Mario to end up on a lake, complete with thin ice. Among a failed attempt by Mario to just go for it, Meggy finds that the solution is sliding to land. Meggy and Mario find Tuxie, only for the penguin to be revealed as an antagonist, as he strands the two on a piece of ice with a tiny tip of a hammer. Meggy finds that Mario's phone still has a signal, but has only 1% left. However, instead of calling for help, Mario orders pizza so that way, they won't starve. Meggy, furious at Mario's stupidity, just sits with her arms folded.
Later that night, Mario and Meggy start to think that it's the end of the two. Just then, the delivery guy, Spider-Man is seen on a jet ski, delivering the long-awaited pizza. Spider-Man sees Tuxie and calls the cops on him, to which the penguin jumps into the water. Mario launches Meggy on her command into the water, to which the icy perimeter launches Tuxie straight at the cops. At this point, he is arrested. Spider-Man explains that Tuxie was the subject of several disappearances, and that he is grateful for their help.
When Spider-Man leaves, Meggy realizes that she and Mario are still stranded, to which Mario eases the mood with the pizza Spider-Man brought, concluding the episode on a happy note.