Jeffy is a character of the SML videos. He is the former son of Nancy and the late painter, Jacques Pierre Francois and the adopted son of Mario and Rosalina.
He is also known as Jeffy Jeffy and Jeffy Francois-Jeffy.
Jeffy likes to spank his diaper, play with his cat piano, put his pee-pee in stuff, put his pencil up on his nose, poop his pants, throw stuff and lock people out of the house.
He also likes pencils, prank calls, chocolate cakes, swearing, money, cookies, Santa Claus, giraffes, marshmallows on pan cakes, and his giant duck.
He dislikes his birth mother, green beans and being called a bad boy.
Jeffy also callls giraffe "gi-d-raffe" and frog "fwog".
Jeffy is a retarded, childish, and short tempered 12 year old boy. In some videos, Jeffy can also be arrogant and short-tempered.
Overall, Jeffy is retarded which can explain why he acts stupid. His birth mom beats him so that could explain why he acts defiantly.