Though JubJub himself didn't seem to mind (as opposed to Boopkins himself, who would immediately summon his father if he were ever abused), both Boopkins and Tari criticized Mario for his abuse, and once he was reunited with
his father (and getting kicked away yet again), Joe Boopkins wasted no time in punishing Mario for his actions.
He has mistaken Ghost Rider's (back of) shirt as his father, technically leading him to join the gang.
After his debut, he started to hang around with SMG4's Gang and became friends with the main cast but later joined SMG3's Gang in S̶M̶G̶4̶: I Can't Believe It's Not SMG4! becoming one of the seven secondary antagonists of the The YouTube Arc. He was assigned to prevent Fishy Boopkins from meeting Mario and SMG4 and succeeded.
Personality
Though he did not immediately know that Fishy Boopkins was his brother, he quickly grew attached to him. He also is attached to his father. Shortly after he was hatched, he wondered where he was. Despite being innocent, he ended up becoming a member of SMG3’s gang. SMG3 chose him to represent Fishy Boopkins, as he was his brother. Presumably he didn’t know that SMG3 was plagiarizing SMG4, as he was born after the events of the Anime Arc.
Powers and Abilities
Like his brother, JubJub can scream extremely loud. However, he can still hear his brother while he is doing this, and will cease to do so if Boopkins requests him to stop.
Like his brother, he apparently has the ability to summon his dad by being in contact with water, though it was likely that his father had been looking for him at that point.
Like his brother, JubJub seems to be rather resilient, as he manages to withstand being kicked by Mario multiple times without being injured. He also survived a massive explosion that was supposed to destroy Beeg SMG4.
He can play music from his mouth if he puts his hand on a record player.
JubJub can also be used as a spare tire but JubJub has also the right to reject this ability too.
When kicked, Jub Jub can be used as an indestructible projectile that can smash through virtually anything he collides with, including a barrage of deadly security lasers.
Trivia
Joe Boopkins punishing Mario for bullying JubJub is similar to him punishing people for abusing Fishy Boopkins.
He was not named by his brother or his father. Instead, he came up with his name himself.
Though he did not see his dad upon first being born, JubJub seemed to know at some level who his father was.
Mario kicking him around like a football is a reference to Kyle Broflovski's behavior in earlier seasons of South Park, in which he kicks his brother like around like a football despite his brother's protests. However, Fishy Boopkins does not engage in this behavior himself.
He makes a similar noise when he eats that his brother Fishy Boopkins does.
Like his brother, he does not speak in subtitles, though he speaks much less often.
Though he is technically a fish, he happens to resemble a rubber duck. This is most likely why Tari adores him.
It is unknown where his body appearance came from, though it's possibly original, like Saiko Bichitaru or Tari.
While Fishy Boopkins is typically referred to by his last name, he is less often referred to by his first name.
He has some similarities to Luigi. Both are younger brothers and are associated with the color green. And they both have similar powers to their siblings.
