Jeffy Jeffy, known simply as Jeffy, is the tritagonist of the SuperMarioLogan franchise, and later the secondary deurtagonist of the SuperMarioLogan franchise. Known for being a foul mouthed, ill-behaved, idiotic, perverted young teenager with an unusual personality and a strange choice of clothing. He is the adoptive son of Mario and his wife Rosalina.


Jeffy was born in a porta-potty at 7 Jeffy Street in Paris, on August 21, 2004 to Nancy and Jacques Pierre François. Nancy, a prostitute, was very abusive towards Jeffy for unknown reasons. At some point in his life, Jeffy moved to the United States with his mother and possibly his father. Jeffy was then dropped off at Mario and Bowser’s apartment because his mother was tired of his antics. Jeffy lived with Mario and his family in the apartment (causing havoc around the house, especially towards Mario) before being evicted from the apartment and having to relocate to the new house. After his wealthy father committed suicide and willed his money to Jeffy, Nancy returned to reclaim Jeffy in order to receive Jacque’s money. After Nancy was arrested for child abuse, prostitution, and much more, Mario chose to officially adopt Jeffy as his son. Jeffy then resumed living with Mario, and continued to cause much mischief around the house


Jeffy is somewhat taller than the average teen, with a lanky and short posture. He wears a blue bicycle helmet, usually has a pencil shoved up his nose, along with a yellow t-shirt that says “Jeffy,” his name, on it. He wears short dark blue jeans with a diaper outside of it, which he occasionally spanks. According to Jeffy, the diaper is on the outside of his pants so the diaper doesn’t get dirty. Jeffy wears black Adidas sneakers. His biological appearance seems to be his blue eyes inherited from his mother, and his dark brown hair inherited from his father. His face is oval shaped with two teeth and has a round nose, along with two eyelashes and a unibrow.


Jeffy has displayed acts that can be seen as outright idiotic. He has a bad habit of spanking his diaper placed outside of his pants. When he is called a “bad boy,” he tends to have a meltdown by throwing his head onto any surface, but calms down when he is called a “good boy” (but this doesn’t happen after the episode Jeffy Loses His Pencil!). However, he could have even more of a breakdown, by swearing and being rude towards Mario and Rosalina . He likes to put his “pee-pee” in various objects, especially Cheerios cereal boxes. He is also afraid of the most retarded things such as animals, toilets, snow, ostriches, and the flu shot. His mother delivered him to Mario because she did not want to look after him (according to Jeffy). Not much is known about his relationship between Bowser Junior and Joseph, despite the fact that they both called him “awesome” after once surviving a game of “Russian Roulette.” Rosalina is more loving and caring towards Jeffy to the point where she acts like a motherly figure and calling Mario off whenever he gets angry at Jeffy.
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However, Jeffy has been shown to act smart, but in a dumb way at times, such as in Jeffy’s Homework! when he reasoned that the equation 8-4=8, since they are taking 4 out of the equation, even going on a profanity-laced rant. Later, in Jeffy’s Bedtime!, he called I-Am-Sam, the tall character in Green Eggs and Ham, a liar since he claimed that he liked the green eggs and ham, but the illustration clearly shows that he didn’t eat the ham at all, and, despite suffering from mental retardation, Jeffy is an extremely skilled painter, result of his former father being a famous painter. According to him, he used to live on 7 Jeffy Street before being dropped off at Mario’s door. Jeffy tends to soil his pants often. Sometimes, Jeffy can be even more demanding than Junior, as seen in Jeffy’s Bedtime!, where he demands that Mario and Rosalina make his green eggs and ham, in “Jeffy Gets Potty Trained!”, and when he demands that Rosalina give him marshmallows instead of peas, in “The Hitman!”, where he wanted Jello after Mario gave him green beans, he refused to eat his McChicken Nuggets because he wasn’t given 20 toys and threw them away, in “Locked Out”, where he demanded for chocolate cake, cried when Mario didn’t give him it, and locked Mario out to enjoy the cake, especially in front of Mario, and in “Jeffy Gets Help”, when Jeffy yells, screams, and throws a temper tantrum because Mario said that he would not watch SpongeBob.
He also flips his desk in “First Day Of School!” because the teacher assigned a 10-page essay that was due the next day and cusses (mostly the F-word) at Jackie Chu. Sometimes Jeffy seems to have a prankster personality as in “Jeffy’s Cellphone!”, where he prank calls several places, including an employee named Josh, and in “Shrek The Babysitter!”, where he locks Shrek in the bathroom with the help of Junior. During both of these videos, he seems to be less unintelligent, causing many fans to think that this could be a normal version of Jeffy, despite all of his intelligent moments in the series. Some people think Jeffy pretends to be retarded. When his real mother Nancy tried to claim him back, Jeffy begged Mario to let him stay and promised to be a good boy (and kept his promise by not playing the cat piano when he went back inside), indicating that he loves Mario very much. Jeffy’s obsession with swearing may be from his mother and the way she acted in front of him.

Character Information

Date of Birth:August 21, 2004 (age 13 1/2)
7 Jeffy Street, Paris, FranceNicknames:

Bad Boy
Good Boy
Jeffis (Black Yoshi)
Mario’s Pet Retard (Black Yoshi)
Son (Mario)
Bad Jeffy
Little Shit(Mario and Nancy)
Kid (Santa Claus, Hansel, and Brooklyn T. Guy)Smart Jeffy
Poop Monster
Sleeping Angel
Little Donkey (Shrek)
Retard (Bully Bill, Judy Nutkiss, Black Yoshi and Mario)
Slugger (Rosalina)
Sweetie (Nancy)
Baby (Nancy)
Retarded Donkey (Brooklyn T. Guy)
J-Fee (Tyrone Calvin Nutkiss, Goodman, and Toad)
Jimmy (Goodman)
Poopy Butt
Boss (Bowser Junior)
Dumb (Jackie Chu)


Spanking his diaper
pooping his pants
making cat noises with his Cat Piano
putting stuff in his nose
saying “Why?”
putting his “pee pee” in Cheerios and other foods
yelling “Uh!”
making animal noises
throwing and/or breaking things


School Student
Dominos Pizza Deliverer (formerly)

Nancy (biological mother)
Jacques Pierre François (biological father; deceased)
Mario (adoptive father)
Rosalina (adoptive mother)
Luigi (adoptive uncle)
Harold Wilfred (adoptive great grandfather)
The Alien (adoptive grandfather)
The Alien’s Wife (adoptive grandmother)
Scooter (Clone)
Baby Peach (adoptive sister)
Mama Luigi (adoptive cloned uncle)
Puss Hole (son; deceased)
Puss Hole 2 (daughter; deceased)
Jeffy Junior (son; deceased)
Cheerios (significant other)

Portrayed by:

Lance Thirtyacre −
Anthony Miller (formerly; animal noises) − Logan Thirtyacre (1 2 Switch Bodies! and Jeffy The Rapper!; moving mouth) − Chris Netherton (Jeffy’s Brain!)

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