Principal Brown: Why don't you tell her [Penny]?
Gumball: Because I prefer my heart beating safely inside my chest rather than being held in front of my screaming face.
Gumball and Principal Brown make a pact to tell each other's girlfriends about problems they have. But when Principal Brown doesn't go through with his part of the bargain, Gumball goes to extraordinary lengths to force him.
Tropes:
- And Show It to You: Discussed. As seen in the page quote, Gumball is afraid Penny will do this if he tells her about her annoying laugh.
- Annoying Laugh: Penny has recently started snorting heavily while laughing, which annoys Gumball enough to create the pact.
- Big Brother Is Watching: When Gumball tries to reveal the truth about their pact to Simian, Principal Brown starts stalking Gumball using the security cameras and claiming that he has control over the whole school.
- The Cake Is a Lie: Gumball goes to great trouble to get Miss Simian to fix her breath, but as soon as that's done, Principal Brown brushes off the idea of telling Penny about her laugh.
- Continuity Nod: At the start of the episode, Gumball is singing along to a recording of the song Darwin wrote about Carrie in "The Matchmaker".
- A Day in the Limelight: Another one for Principal Brown.
- Downer Ending: Gumball's plan to expose Principal Brown's misdeeds and Brown's Heel Realization end up revealing their entire pact, making both of their girlfriends mad at them.
- False Reassurance: When Principal Brown asks Gumball if Penny and Miss Simian are right behind him, Gumball says they aren't; they're to the left of him.
- Half the Man He Used to Be: To avoid sharing a bus seat with Principal Brown, Teri splits herself in half.
- Humiliation Conga: Gumball's part of the pact results in him being mutilated over and over by Miss Simian's breath, and with a pencil stuck... somewhere.
- Inspiration Nod: The episode's basis on Strangers on a Train is acknowledged when Gumball first proposes the pact. Principal Brown mistakes Gumball's plan to point out their girlfriends' flaws for straight up murdering them (which was the deal in the film).Gumball: Yeah, I take care of Simian and you take care of Penny, right?
Brown: But it'll have to look like an accident!
Gumball: What!? I meant take care of the laugh and breath thing!
Brown: Oh yes, that's a much less illegal idea! - My God, What Have I Done?: Principal Brown, at the end, finally realizes he's been horribly abusing his power and should have just fulfilled his end of the deal.
- Noodle Implements: After Gumball told Miss Simian that her breath stinks, his only description of the aftermath is "I didn't go to the hospital— the nurse said it would be more dangerous to surgically remove the pencil."
- Pet the Dog: Miss Simian genuinely congratulates Gumball for getting a 1 out of 3 on his test, saying that it's his best score he's ever gotten.
- Right Behind Me: After Principal Brown accidentally antagonizes both Penny and Miss Simian over the intercom, he sees Gumball pull an "Oh, Crap!" face, implying both of them had come up to exact revenge. He says this trope verbatim, to be told no, they're not. They're right next to him.
- Sanity Slippage: Both Gumball and Principal Brown grow crazier as the episode goes on when the latter refuses to finish the pact.
- Smell Phone: When Gumball attempts to tell Miss Simian about her breath from the safety of a pay phone, the stench carries through the phone line.
- "Strangers on a Train"-Plot Murder: The episode is a Whole-Plot Reference to the Trope Namer; not only do the two protagonists making a pact to "fix" the other's problem, one of the duo backs out after the other has done the deed.
- Stripped to the Bone: Gumball is reduced to bones upon smelling Miss Simian's breath while trying to slingshot a mint into her mouth (this is a step up from three of his classmates, who were reduced to dust). He could still smell it afterward, somehow.
- Taking You with Me: Gumball do this towards Principal Brown's threats. When Gumball said that he's going to be expelled anyway. Might as well tell Miss Simian that Principal Brown that makes him do it.
- This Is Unforgivable!: Gumball goes completely berserk when Brown chickens out of his half of the deal. Though considering the amount of pain he endured with his part, his anger is somewhat justified.
- Threat Backfire: Gumball misinterprets Principal Brown's threat to frame him for stealing the money from the school's safe as a bribe offer, which he happily accepts.
- Two Rights Make a Wrong: Gumball turns on the intercom for the entire school to hear Principal Brown's Evil Gloating, which turns out to be unnecessary when Brown is reconsidering his actions in using Gumball as a pawn and made worse when Brown mentions Gumball's complaints about Penny's Annoying Laugh. It ends how one would expect.
- Wilting Odor: Miss Simian's breath is so terrible that just the mere smell of it causes multiple students to disintegrate. Gumball even attempts to shoot a breath mint into her mouth with a blow gun, but fails.
