Oingo

Oingo is a minor antagonist appearing in Part III: Stardust Crusaders.

Personality
Oingo is often overconfident due to the deadly ability of his stand to disguise himself combined with Boingo's stand ability to predict the future. This overconfidence backfires, however, when Oingo becomes the downfall of the prediction he trusted in. He had a really close relationship with his brother Boingo and tried to protect him from all the bad people that exist in the world (even though both of them were criminals). He also was capable of attacking someone if he didn't like the way they looked, showing a violent personality. When his shy brother Oingo promised to get revenge for him he became really proud of his younger brother.

Stardust Crusaders
Oingo is first shown threatening one comic artist interested in Thoth to stay away from Boingo, and then decides with help from Boingo's stand Thoth to wait four hours for the next bus, as the stand warms them about an accident with the bus. The brothers then look into Thoth for the next prediction and realize that they were meant to poison the Joestar group's tea. Oingo secretly assaults one of the waiters at a nearby restaurant and takes his place. At the same time, Jean Pierre Polnareff lets a cigarette fall, which points to their restaurant.

Initially, the group decide to order tea, but a suspicious Joseph Joestar decides to order the unopened coke instead. This seems to prevent Oingo from poisoning the drink at first, but an angry customer reacts to the warm coke he was served, causing the Joestar group to order the tea that Oingo successfully poisons.

Right as the group is about to drink their tea, Iggy eats another customer's cake and causes the Joestar group to abandon their tea to take care of Iggy and leave shop, which makes Oingo and Boingo angry. Eventually, following Thoth's prophecy, Oingo punches a nerdy-looking stranger and frightens him into dropping his wallet, giving the two money and temporarily pacifying them for their failure.

Following Thoth's next prediction, Oingo then tries to make Jotaro eat a bomb that looked like an orange. However, Joseph and Polnareff return and Oingo is forced to disguise himself as Jotaro in order prevent them from attacking him. The disguise backfires and Oingo is dragged into the same car where he placed the bomb.

Oingo initially tries to prevent the bomb by throwing it out of the window, but Iggy fetches the bomb and brings it back into the car. Polnareff then demonstrates a cigarette trick, in which he lets a cigarette fall into his mouth, and calmly breathes out the smoke, and asks "Jotaro" to show him the trick with five cigarettes. Oingo pulls off the trick, but fails when he is forced to prove himself by drinking the juice while the cigarettes smolder. The result causes him to spit it out, and his stomach eventually acts up when he becomes paranoid that Joseph and Polnareff are secretly testing him to see if he is really Jotaro. Polnareff decides to race "Jotaro" in eating oranges the fastest but Oingo, realizing the orange that Polnareff picked up was the bomb, stops him from doing so and suggests that since the "orange" was picked up by Iggy, it could have been contaminated in any kind of unsanitary location.

Fed up with having to deal with Joseph and Polnareff, Oingo runs off to the rocks to escape, using a bathroom break as an excuse, and resolves to escape by changing his appearance behind the rocks again. However, Polnareff, considering the truth of "Jotaro"'s statement, throws the disguised bomb out of the car. Oingo then accidentally steps on the bomb, causing it to blow up and split his face in two.

Boingo then arrives and resolves to defeat the Joestar group on his own, causing Oingo to become proud of his younger brother's growth. However, the man they assaulted earlier returns with other thugs, who beat up the two brothers and send them to the hospital. Meanwhile, the real Jotaro returns from visiting the hospital, and, happening to be thirsty, picks out an orange to eat. Oingo is later mentioned by Hol Horse, who convinces Boingo to help him asking if he doesn't want to avenge his brother.

Trivia

 * Due to copyright laws, Oingo and Boingo were renamed Zenyatta and Mondatta respectively in the Viz translation, after The Police album of the same name.