The cheerleaders of Elmore Junior High are spending their lunch break practicing on the field. Gumball is spending his own time spectating over them (Penny, in particular), taking a reluctant Darwin along. At first, the day appears to be sunny, with the cheerleaders performing their routine flawlessly and Gumball rooting for Penny but Darwin snaps Gumball out of his euphoria, making him realize the rainy condition, the routine gone wrong and his cheering over Penny's mishap. This happens in time for him to see Leslie walking Penny off and hugging her, causing the jealousy in Gumball to intervene. Jealousy assumes direct control of Gumball's body and angrily races off towards Leslie, blowing through many obstacles along the way. Unfortunately, he uses too much of his energy on the obstacles, passing out upon reaching Leslie and Penny, who have walked off without noticing him.
In the cafeteria, Gumball spies on Leslie and Penny, whose envy once again assumes control over him and causes him to scornfully mock Leslie. He charges in to attack Leslie, who easily brushes him aside and walks away with Penny. Furious at his own spiteful emotion, Gumball fights back for his body, but is overpowered. He is knocked out by his own limbs.
With Gumball unconscious, his body is under the unadulterated influence of his Jealousy. He attempts to frame Leslie for the theft of a trophy, but fails for not concealing his tracks. In the wake of the incident, a trail of glass behind was left behind after Gumball had smashed the trophy case, Leslie's locker had already been pried open after he himself attempted to place the trophy in it, and in his own locker are herbicides, vandalized pictures of Leslie, and the crowbar Gumball used to force Leslie's locker open. Upon being caught, Jealousy gives a dazed Gumball his body back, leaving him to take the fall.
Everyone involved gets called into Principal Brown's office, where Gumball attempts to apologize to Leslie. His Jealousy intervenes and spews a long string of insults at Leslie. Believing to be locked away in prison as a result, Gumball sadly resigns to his fate, but Principal Brown notifies him that he will not be incarcerated. Upon hearing this, an ecstatic Jealousy repossesses Gumball and attempts to flee to Mexico. His plan is foiled by his inability to open the door, repeatedly running into it until knocking himself out. Gumball, lying knocked out on the ground, agrees to make amends with Leslie.
The two try to bond with a walk in the park. Gumball benignly offers Leslie a seat on a shady bench, which Leslie gingerly accepts. All is well until the trap set by Gumball's Jealousy is triggered - Leslie's spot is slathered with superglue, allowing Gumball to unleash snails and other herbivorous insects upon him. After a few mildly clever remarks, Gumball departs, leaving Leslie to die.
At the school cafeteria the next day, Penny and Darwin remark on the friendship formed between Gumball and Leslie. Bursting through the cafeteria doors is a naked and partially eaten Leslie, calling Gumball insane. Penny immediately rushes to his side, prompting Gumball's Jealousy to return. Gumball, with no traces of his former self visible, pounces on Leslie and brutally rips his petals off one by one. Darwin rushes over and, with Penny's help, restrains a feral Gumball from hurting Leslie further. By then, everyone notices that Gumball is not himself. Carrie formulates a plan and leads them all to her house.
Knowing full well that Gumball's Jealousy had gotten the better of him, Carrie has called everyone to her room to perform an exorcism. They put Gumball in the center of a circle of candles and occult markings while chanting "Jealousy be gone..." repeatedly. Much to Carrie's surprise, the exorcism is successful, and the Jealousy is expelled from Gumball's body and manifests into a lumpy green ball of ectoplasm. Penny steps into the circle to try to help Gumball, but breaks the protection ward by doing so, releasing Jealousy from his prison. He immediately wreaks havoc on the room, trashing anything and everything that he envies and possessing Leslie, Carrie and Darwin in order. He soon declares an ultimatum: if he can't have Gumball, then nobody can, and prepares to explode. The only way to be rid of him is if Gumball overcomes his envy of Leslie. But he cannot so long as Penny and Leslie are dating, to which Penny responds that they're not dating, they're cousins. Now that Gumball is no longer jealous of Leslie, Jealousy disappears. The five kids lie exhausted amidst a pile of Carrie's belongings. Carrie gives Gumball a friendly punch in the arm, which causes Penny to blurt out a similarly-lengthy insult at her; Jealousy has not been completely driven away. The episode ends with everyone shocked and saying "Wow."
It is also revealed that Penny is jealous of Carrie and Gumball.
This was the first episode where Leslie is seen naked.
This was the second time we see Leslie without his flower pot. The first time was in "The Party." However he was not pixelated in that episode. The third time is in "The Boombox" where he is again pixelated.
In Latin American Airings, Gumball (Who was Possessed by Jealousy) Said He's was going to escape to Africa.
When Gumball tries to kick Leslie in midair, he yells out "Hadouken!", a reference to Street Fighter.
The circle of pepper used to isolate Jealousy during the exorcism is a reference to putting down a ring of salt. In some beliefs a ring of salt is used as a protective barrier against demons and other spirits.
The part where Carrie, Penny, Darwin and Leslie try to exorcise Jealousy out of Gumball is similar to the scene in the 1973 movie The Exorcist.
The character of Jealousy being green and turning its victims green is a play on the words "green with envy."
Leslie with a vacuum is a homage of Ghostbusters series.
The AB/CD logo on the vaccum references the AC/DC band logo, as the red background color, lettering, and lightning bolt between the letters are the same.
When Leslie said, "Well, someone found it entertaining," one of the frames in the shot just shows the background, but no characters.
When jealous Gumball is running through the football track, Bobert and Teri are seen running along with other students in the rain. However, in "The Robot," Bobert shorted out when he got wet, and Teri couldn't have stayed in the rain, because she is made of paper.
When Tobias is seen walking in the background in a scene in the cafeteria, he has his Season 1 design.
On the DirecTV captions, when Penny says, "Fat-faced people have feelings too you know, Gumball." it directs that Darwin says it.