[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/the_bob_next_door.jpg]]
[[caption-width-right:350:Going by this promotional picture, you'd almost swear this was an EnemyMine between Bob & Bart.]]

Bart fears that his new neighbor might be Sideshow Bob -- and his suspicions send the Simpsons into a bizarre case of mistaken identity.
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!! Tropes:

* ActorAllusion: As noted in CelebrityParadox, the people listed by Homer and Marge as sounding like Sideshow Bob are characters played by Bob's voice actor.
* AlliterativeName: '''Wa'''lt '''Wa'''rren.
* AmbiguousSyntax: "Bart Simpson will die." [[LampshadeHanging Lampshaded by Marge]].
* ArsonMurderAndJaywalking: When Walt shows the Simpson family Bob's room, a lot of pictures of Bart and Krusty with knives pinned in them are shown, as the words are inscribed "Kill Bart!", "Kill Bart!", "Kill Krusty Too!" and "Buy Milk!"
* ArtisticLicenseLaw: At Five Corners, Bob intends to kill Bart in such a way that the crime takes place in all five states (Bob stands in the first, fires the gun in the second, the bullet travels through the third, hits Bart in the forth, who falls dead in the fifth), thus making it impossible to prosecute. In actuality, this would have resulted in ''federal'' prosecution for first-degree murder (with a probable death sentence under the circumstances), given that it crossed state lines at Five Corners.
* BatmanGambit: Bart and Milhouse attempt this on Walt by enacting a Creator/GilbertAndSullivan play, thinking Bob can't resist the temptation of joining in if it's really him, but he easily shrugs it off, claiming he prefers "southern style music".
* BroadStrokes: Sideshow Bob seems to have resumed his hatred of Krusty despite making amends and hanging out in the previous season. However, nothing in this episode said it ''couldn't'' be a prequel episode.
* CassandraTruth: Bart believes that Walt Warren is Sideshow Bob just based off his voice. He's right and he's almost killed because he believed that he was wrong.
** Walt Warren himself. He was set up to look like Sideshow Bob and he had a difficult time telling people who he really was. He even tried warning Bart that he was going to die, but people obviously didn't believe him.
* CelebrityParadox: PlayedForLaughs with Marge and Homer assuring Bart that lots of people sound like Sideshow Bob: Frasier from ''Series/{{Cheers}}'', [[DepartmentOfRedundancyDepartment Frasier]] from ''Series/{{Frasier}}'', and Lt. Commander Tom Dodge from ''Film/DownPeriscope''. [[Creator/KelseyGrammer Guess who]] played these characters.
* ComicallyMissingThePoint: Homer failed to realize tacos are called tacos in both English and Spanish.
* ComicBookTime: Bob is shocked to find that Bart hasn't finished reading ''Literature/HarryPotterAndTheHalfBloodPrince'', exclaiming "It's a four-year-old book!" ("I'm a slow reader!") The exchange makes little sense if you're taking Bart's age at face value, as four years earlier he would have been only six and would have been a little young to be reading the ''Harry Potter'' series at all--slow reader or not, it's only natural that he wouldn't be very far into it now. (On the other hand, [[InsufferableGenius this is Sideshow Bob]].)
* ContinuityNod: This episode makes several {{Call Back}}s to some, if not most of Sideshow Bob's appearances on the show.
** [[Recap/TheSimpsonsS1E12KrustyGetsBusted Walt explains that Bob has big feet, while he himself has small feet, which helped Bart prove Krusty's innocence.]]
** [[Recap/TheSimpsonsS5E2CapeFeare Bart mentions that Sideshow Bob could never resist singing along to a Gilbert and Sullivan song, referring to the HMS Pinafore.]]
** [[Recap/TheSimpsonsS6E5SideshowBobRoberts Mayor Quimby releases Sideshow Bob once again although this time due to the economy in bad shape and not because of demands from the townspeople orchestrated by Birch Barlow.]]
** Five Corners was [[https://youtu.be/n3SNGhOKw10 first shown]] in [[Recap/TheSimpsonsS6E4ItchyAndScratchyLand Itchy and Scratchy Land]]
* {{Determinator}}: Bob in probably his most extreme instance to date: he puts the "surgical face-switching" plan in motion under the belief that countless AmusingInjuries during his time as Krusty's sidekick have left him completely insensate in the facial area. When that quickly turns out not to be true, he goes forward with the plan anyway.
* DuctTapeForEverything: As Sideshow Bob explains his GrandTheftMe of Walt, he uses excessive duct tape all over the place to tie Bart to a car chair and gag his mouth; as Bart tries signalling Bob to remove the tape, he puts more duct tape on his already taped mouth.
* EatTheCamera: Ends the first act, when Bart runs screaming from "Walt" among recognizing the voice as Sideshow Bob, he runs right into the camera, his mouth turning the frame black.
* ExactWords: When finally having Walt and Bart at gunpoint, Bob, love seeing his old face, gives Walt the chance to choose which state he wants to die on. Walt chooses Hawaii, which is not part of the states that comprised of the Five Corners and most likely said that intentionally.
--> '''Sideshow Bob:''' Choosing privilege revoked.
* {{Foreshadowing}}: As Quimby announces low level criminals are being released from prison, you can see "Walt" leaving.
* HiddenDepths: Even though he's a minor offender, Walt managed to perfectly plan and execute his escape from prison, which could mean that either there's more criminal behavior in Walt's past than has been revealed thus far, or that while he and Sideshow Bob were cellmates, Bob bragged about his exploits enough for Walt to pick up a few pointers.
* JurisdictionFriction: {{Averted|Trope}}. While Sideshow Bob is at Five Corners (a place where five states meet) by the time Chief Wiggum finds him, police officers from the other states show up to arrest Bob and his only choice is where he'll be arrested.
* LameLastWords: Bart nearly has some after Bob spoils a four-year-old ''Harry Potter'' book for him.
-->'''Bart:''' I'm a slow reader!
-->'''Sideshow Bob:''' A fitting epitaph.
* LateArrivalSpoiler: In-universe example. Sideshow Bob is surprised Bart doesn't know ''[[Literature/HarryPotterAndTheHalfBloodPrince Snape killed Dumbledore]]'' because it's been 4 years since the book has been published.
* MagicPlasticSurgery: There's zero scarring, stitching or visible damage of any kind to indicate where Walt and Bob switched faces, even though tugging on a single loose thread is enough to undo the work.
* NoodleIncident: The waitress laments that every man she flirts with is either gay or has no face. Now, the "has no face" part was shown, but the gay part wasn't.
** Bart gets flashbacks of dealing with Sideshow Bob, one of them is a clip of him tied upside down on the Art/StatueOfLiberty; this scene is not from any actual episode.
* OffOnATechnicality: Bob's plan to kill Bart was shooting from a state while his gun-holding hand was at a second state; having the bullet cross another one; having Bart being hit in a fourth state and falling dead in the fifth. No single action could be prosecuted or so Bob believes. Even he seems to realize it doesn't make sense since he just decides to shoot Bart when he keeps jumping and says that if anyone asks he followed his plan.
* OhCrap:
** Bart when he believes Walt Warren is Sideshow Bob. And he's right.
** Homer when Flanders's relatives moves in.
* PapaWolf: When Walt wearing Bob's face shows up to warn Homer and Marge, Marge sprays water in his mouth and Homer slams the windowsill on his neck making it clear he is gonna kill him this time.
-->'''Homer:''' Alright buddy, I'm gonna do to you what you should have done to my son a long time ago.
* ParrotExpowhat: When Bart recognizes "Walt's" voice and screams, "Aaaah! Sideshow Bob!", "Walt" pretends not to understand and asks, "Side-what Whom?"
* PhotoshopFilterOfEvil: As Bob starts discussing his murder plan to Bart, the picture goes to some sort of color/black-and-white negative filter, indicating the future action of the plan detailed in slow-motion.
* PoliceAreUseless: Subverted. Bart called Wiggum and had him follow Bob's car using a tracking device. Police officers from other states [[WhereTheHellIsSpringfield (Texas, Minnesota, New Jersey, and California)]] also show up to prevent Bob from killing anyone in a different state.
* PoorCommunicationKills: Almost. "Bart Simpson will die" was [[WarningMistakenForThreat a warning, not a threat]]. When Marge points out Walt's poor choice of words, being "open to interpretation" , he sheepishly responds "I'm not a writer".
* PrisonRape: Implied. Walt says that Bob measuring his face is better than what his last cellmate did.
* RakeTake: Happens when Bob tries following Bart through all five corners of each state in an attempt to kill him... and accidentally steps on a rake that appears out of nowhere, a CallBack to "[[Recap/TheSimpsonsS5E2CapeFeare Cape Feare]]".
* ScreamingWoman: The waitress among accidentally unraveling the string that holds Walt's face onto Sideshow Bob's head. It's the same scream Creator/TressMacneille used for Charlotte Pickles on ''WesternAnimation/{{Rugrats}}''.
* ScrewTheRulesIHaveMoney: Or rather "Screw the rules, you don't have money!" Homer takes advantage of the city's financial crisis by speeding and passing another car by using the sidewalk since the city can't afford to punish him for it.
* ShoutOut: Bob said his plan to kill Bart would be the greatest murder ever since [[Literature/HarryPotterAndTheHalfBloodPrince Snape killed Dumbledore]].
** Bob's plan hinges on ''Film/FaceOff''-esque surgery.
** Walt Warren sounds like Creator/JimmyStewart.
* SouthOfTheBorder: Falling for Walt's look, a waitress misleads the Simpsons into going to Mexico.
* SubvertedSuspicionAesop: After spending half the episode trying to prove that Walt was really Bob, Bart eventually decides he was wrong and even takes him up on his offer to go a trip. It's only after he gets in the car does he find he was right and that he really ''is'' Bob. {{Subverted}} with TheReveal that Bart was never convinced Walt wasn't really Bob and before leaving, called Chief Wiggum, requesting that he track him.
* TaughtByExperience: Bob doesn't fall for Bart and Millhouse singing Three Little Maids, [[Recap/TheSimpsonsS5E2CapeFeare most likely remembering the last time he tried that]], [[note]] Singing the HMS Pinafore [[/note]] he was caught up in song, that by the time he finished, Wiggum and his cops arrested Bob on the spot. [[spoiler: When he finally reveals himself to Bart, he [[ArsonMurderAndJaywalking sings Behold the Lord High Executioner]] as means to celebrate]].
* WarningMistakenForThreat: Walt, Sideshow Bob's cellmate, writes, "Bart Simpson will die," which other people take as a death threat to Bart, when he's actually referring to Bob planning to kill Bart. Also not helping Walt was the fact that he and Sideshow Bob had their faces surgically switched ala ''Film/FaceOff'' as part of Bob's escape plan, so it looked like Bob was still in prison and writing that threat.
-->'''Walt Warren''': I tried to warn you by writing "Bart Simpson Will Die" on the walls, bu-but you ignored me.
-->'''Marge Simpson''': You have to admit, "Bart Simpson Will Die" was kind of open to interpretation.
* WhamLine: Just when Bart is convinced Walt Warren is not Sideshow Bob, this happens.
--> '''Walt Warren''': You don't have to call me Mr. Warren anymore. You see Bart, you were right all along. I am '''SIDESHOW BOB'''. [[ArsonMurderAndJaywalking And now I'm free to sing all the Gilbert and Sullivan I damn well please]].
* WrongGenreSavvy: Years of being Krusty's sidekick made Bob immune to pain. Or so he thought.
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