[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/separatevocations.jpg]]
Episode [=8F15=]\\
First Aired 2/27/92

When the results of Bart's vocational survey suggest he'd make a great cop and Lisa learns her dreams of becoming a professional sax player are doomed by genetics (she has stubby fingers, which would make saxophone playing impossible, even though she doesn't exhibit any problems), their roles at Springfield Elementary are reversed: Bart becomes a hall monitor who cracks down on school misbehavior (after surviving a run-in with Snake during a police ride-along) while Lisa becomes a rebel who smokes with the bad kids, gets detention, and pulls off a teachers' edition textbook heist that could get her expelled.

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!!This episode contains examples of:

* BreakTheCutie: Learning that the only thing she is worthy of is being a housewife and being rejected from becoming a professional saxophone player due to her stubby fingers broke Lisa down to the point of becoming a rebellious student.
-->'''Lisa:''' Dear log: This will be my last entry, for you were a journal of my hopes and dreams. [[{{DespairEventHorizon}} And now, I have none]].
* EvenEvilHasStandards: When Lisa points out that Bart used to appreciate the value of a prank, Bart responds, "Yeah, but even I had my limits."
** Even Lisa realized she's gone too far, but done it anyway, and cries.
* EpicFail:
** Snake attempts to run over Bart, only for his car to get caught in the narrow pathway and catapult him out the windshield, injuring him horribly.
** Marge tries to console Lisa by telling her a story from her childhood about how she wanted to be an astronaut, but her sisters told her women can't be astronauts because they'd "Distract the men." Little Marge insisted she would too become an astronaut and in the future people would live on the moon. Marge finishes her story by saying her sisters were wrong because there are women astronauts... and that she was wrong about the living on the moon part. Lisa is not amused, especially since Marge misses the point of her own story which would've been more uplifting if she had become an astronaut herself.
* FunWithAcronyms: The Career Aptitude Normalizing Test (CANT)
* InformedFlaw: Lisa's stubby fingers will supposedly prevent her from being a professional saxophone player, but she's never expressed any difficulty with her fingering before or since.
* IneptAptitudeTest: According to the CANT, Bart is best suited to be a policeman, while Lisa will be a homemaker. The machine that analyzes the tests is seen malfunctioning when it gets to Bart's test.
* InnocentlyInsensitive: Lisa bemoans loudly that becoming a housewife is a FateWorseThanDeath, right in front of a hurt Marge.
* TheLancer: Bart becomes one to Principal Skinner.
* PersonalitySwap: After the test results, Bart becomes hall monitor while Lisa fills the role of rebellious prankster vacated by Bart.
* RealityEnsues: Bart quickly learns that firing a gun involves recoil.
* ShoutOut: When Skinner asks Lisa what she's rebelling against, she says "Whadda you got?", the same response as Creator/MarlonBrando's character in ''Film/TheWildOne''.
* SpecialGuest: Creator/SteveAllen as [[ImagineSpot Bart's altered voice]].
* TakingTheHeat: Bart willingly takes the blame for the textbook theft to save Lisa from punishment.
* WouldHurtAChild: Snake has no problems with running over a ten-year-old boy, especially in front of the ''cops''!
-->'''Snake:''' See you in hell, punk!!
* YellowSashOfPower. As hall monitor, Bart rules with ruthless efficiency. The image at the trope's page is a scene from this episode.