The episode starts with the cheerleaders of Elmore Junior High 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.
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'soffice, 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, 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 cannot 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 are not dating, they are 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. Everyone is shocked and say "Wow" in unison, ending the episode.
This episode reveals that Darwin is absolutely satisfied with his life to the point that he is immune to jealousy. This is somewhat contradicted in "The Roots" and "The Night," where Darwin greatly desires a larger fish tank to sleep in.
This was the second time Leslie is shown 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 is possessed by Jealousy) says he is going to escape to Africa.
This is the first time that Carrie's house is seen.
When Gumball opens his locker, various early production pictures can be seen on the door and spilt on the floor. One of them is also seen in "The Curse."
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."
The AB/CD logo on the vacuum references the AC/DC band logo, as the red background color, lettering, and lightning bolt between the letters are the same.
During the investigation of Gumball's locker, when a crowbar falls out, Gumball is seen doing the popular fad "Pokerface."
Penny's relationship with Leslie is a reference to how real-life peanuts are shown to grow once the flower it is connected to starts blooming.
When Leslie says "Well, someone found it entertaining," one of the frames in the shot just shows the background, and no characters.
When jealous Gumball is running through the football track, Bobert is seen running along with other students in the rain. However, in "The Robot," Bobert shorted out when he got wet. Also, Teri helps Penny when she falls, but she could not 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. Carmen can also be seen with her season 1 design at one point.
On the DirecTV captions, when Penny says, "Fat-faced people have feelings too, you know, Gumball," it directs that Darwin says it.
When it is shown that Gumball put the trophy in Leslie's locker, glass footprints are seen. However when the ground is again seen, the footprints are nowhere to be seen. In the next scene when Carrie speaks, the footprints are again seen.
When possessed Gumball wheezes, he wheezes similarly to normal Gumball, instead of his lower-pitched voice.
When Penny gets possessed by Jealousy, the details on her shell go missing.
Leslie: See, he hates me, it's been like this all day!
Gumball: Look, I don't hate you, it's just... I'll explain everything when I get out of prison.
Nigel Brown: Prison? [Chuckles] Gumball, we're not the police.
Gumball: Wait, you mean I'm not wearing handcuffs?
Nigel Brown: Of course not.
Jealousy: Well, then, good luck finding me in Mexico! [Starts slamming himself into Principal Brown's door continuously until he faints; the door finally opens]
Penny: Gumball, please make an effort with Leslie.
Gumball: Yeah, okay.
A Stroll in The Park
[Scene changes to the park, where Gumball and Leslie are walking together]
Gumball: [Sighing happily] I'm pleased we've got to spend this time together.
Leslie: Me, too, Penny was right, we do have a lot in common.
Gumball: Phew, it's hot. Oh, a bench in the shade. [Chuckling][Pats the other side of the bench, showing where Leslie should sit]
[Both of them sigh happily and chuckle]
Leslie: You know, after today, I never thought you and me would become friends.
Gumball: Well, I guess sometimes life is just full of...
[Jealousy pulls a rope, then many slugs, snails, and worms start falling from the tree onto Leslie; Leslie screams and freaks out]
Jealousy: Ah... I see you've met my hungry little friends.
Leslie: [Tries to move, but cannot] I can't move!
Jealousy: That's right, I glued you to the bench. [Laughs evilly] I guess we won't be... "insecting" you at school tomorrow. [Laughs evilly] Wait wait, I-I can do better. [Taking a deep breath] We'll see how pretty you'll look after this, larva boy! [Laughing still] No, still not good enough. [Taking another deep breath] That'll teach you for being a creep...y...crawl- ah... you get the point. [Walks away]
[Scene changes to the school cafeteria as the school bell rings. Penny is eating with Gumball and Darwin]
Penny: I'm so pleased you and Leslie are finally getting along.
Darwin: Yeah, because for a while there, you completely lost it.
Penny: Where is he by the way?
Gumball: Uh... he had to take care of something that was-
Jealousy: BUGGING HIM!
Gumball: [Sing-song voice] Nailed it!
[A door is heard being slammed open. Leslie comes in, partially eaten and injured]
Leslie: PENNY, keep away from him! He's insane!
Jealousy: How did you get away? I glued you to the bench!
Leslie: You glued my pot to the bench!
[The camera shows Leslie, not wearing his pot. The area where it would be is censored]
Penny: Oh, Leslie. Are you okay?
Jealousy: STAY AWAY FROM HER! AHHHHHHHHH! [Runs to Leslie and starts plucking his petals]
Jealousy: She loves me! She loves you not! She loves me! She loves you not!
Penny: [Terrified] DARWIN, HELP!
Darwin: Dude, chill out! [He and Penny restrain Jealousy] We need to do something! I don't even recognize him anymore!
Carrie: I think I know what to do. [Flips her hair]
Putting An End to Jealousy
[Scene changes to Carrie's house. An owl hoots off-screen. Carrie is lighting a circle of candles on the floor of her bedroom]
Carrie: Don't break the circle of pepper. It's our only protection.
Penny: From what?
Carrie: Jealousy. It's taken possession of his body. And it must be EXPELLED!
[Jealousy tries to escape the circle of pepper, pouncing at Carrie, but a green shield keeps him contained]
Carrie: Gumball, if you're there, give us a sign. [She holds up a mirror]
[Gumball shows up in the mirror's reflection; he fogs up the mirror and writes]
Darwin: [Reads] "Writing... in this way... is difficlut." Yeah, that's Gumball, alright.
Carrie: Good, it's not too late. Now, we must present the root of his jealousy. Leslie, [Jealousy growls at Leslie] take a step forward.
Leslie: I... feel like I'm close enough already, how about you guys take a step back?
Carrie, Penny, Darwin and Leslie: Jealousy begone, Jealousy begone, [Voices grows louder] Jealousy begone, JEALOUSY BEGONE, JEALOUSY BEGONE!
[Gumball's face glows brightly and Jealousy is released from his body. The camera zooms of the room, and an owl hoots off-screen again. Back in the bedroom, a green flame circles Gumball's body, trying to get out of the circle]
Darwin: What is that?
Carrie: It's Jealousy, in its purest form.
Penny: [Gasps] Gumball, are you alright?
Carrie: No, no DON'T!
[Penny steps into the circle of pepper and it explodes; Jealousy is released from the circle and starts flying around Carrie's bedroom, cackling]
Jealousy: How come you have more comic books than I have?! That makes me ANGRY! [Throws the comic books at them, but Leslie and Carrie use Darwin as a shield]
Darwin: [Gets hit by three books] Ah, oof, agh!
Jealousy: [Flies into the TV] I want a TV in my room! Hmmmmmm... [Blows up the TV] Your bed's really sturdy, mine's not as well-made! [Throws the bed at them].
Jealousy: Aww, I've always wanted a dimmer switch!
Darwin: What do we do?
Carrie: I don't know!
Darwin: What do you mean you don't know?
Carrie: I just read about it on the Internet, I didn't think it wasn't going to work!
Jealousy: [Throws Carrie's shoes at them one by one] How many pairs of shoes do you need? You don't even have feet!
[A door slams open, revealing an angry Leslie armed with a vacuum cleaner]
Leslie: Hey! Over here, you green freak!
Darwin: Leslie! [He and Carrie join Leslie at the door]
Leslie: [Cocks vacuum cleaner like a shotgun] I've got a vacuum bag with your name on it!
[Leslie turns on the vacuum cleaner. It sucks in Carrie, who gets half her face stuck in the vacuum cleaner's tube]
Leslie: Ah, no, turn it off, turn it off!
[The vacuum cleaner shorts out, releasing Carrie; her face is deformed in the shape of the tube]
Carrie: [Takes a hair out of her mouth] Gross.
Leslie: [Jealousy flies towards him] Aaaah! Omph! [Gets knocked over and possessed]
Jealousy: [Possessing Leslie] I wish I had my own bedroom! Like you! [Points at Carrie, then proceeds to possess her]
Jealousy: [Possessing Carrie] I wish I had my own body! Like you! [Proceeds to possess Darwin]
Jealousy: [Possessing Darwin] Huh... I'm actually quite happy with my life. [Leaves Darwin's body]
Jealousy: And you! [Pointing at Penny and Gumball] You betrayed me... if I can't have you, [Demonic voice]nobody will![Starts to inflate himself]
Darwin: What is he doing?
Carrie: He's gonna explode! Gumball! You have to stop being jealous!
Gumball: I can't! Not as long as Penny is going out with Leslie!
Darwin: [Gets squeezed by the inflating Jealousy] Aah! Penny! You gotta break up with Leslie!
Penny: What are you talking about? We're not dating, we're cousi—
[Camera cuts to outside Carrie's house while Jealousy explodes with a bright green flash. Then cut to Gumball flying backwards in slow-motion]
Gumball: Wait, did you just say he was your cousin?
Penny: Well, duh, everybody knows.
Gumball: Well, duh, I didn't.
Leslie: There's a lot of things you don't know about me, Gumball.
[The slow-motion effect ends and Jealousy implodes, pulling everyone into the center of the room. Everyone is lying down on the ground, panting]
Gumball: I wish you said that earlier.
Leslie: Yeah, so do I.
Gumball: Sorry man, I just didn't know.
Penny: [Stands up and dusts herself off] Well, I think that was a good lesson for you. Jealousy is a pretty ugly thing, Gumball!
Gumball: Yep! [Stands up and straightens his back, making a snapping sound] I get it!
Carrie: Haha, that's okay. [Punches Gumball on the arm] You made it, man!
Jealousy: [Possessing Penny] Get your hands off him, you undead, ectoplasmic, transparent, paranormal, spooky, floating, fringe-flicking freak!
Gumball, Darwin, Carrie and Leslie: ...Wow.