Bart trades places with a rich boy named Simon who looks just like him, but he discovers that Simon's half-siblings are planning to do him in to get his inheritance.
* AIIsACrapshoot: Lenny's Vac-U-Bots have a convenient "Malevolent Sentience" setting.
* BrickJoke: When Mr. Burns tells about his siblings and their early deaths, he mentions that most of them died from eating poisoned potatoes. In a later scene, Queenly offers her brother a potato.
* EvilerThanThou: After Devon and Queenly think they got rid of their half-brother, Queenly tries to make Devon eat a poisoned potato when he declares they'll split the inheritance.
** Homer is right to be mad at Bart for playing one prank too many as is everyone else.
** Lisa also qualifies by pointing out that Simon is nothing like Bart.
* KarmaHoudini: Devon and Queenly never receive any comeuppance for trying to get rid of their half-brother. Or at least Queenly, assuming if she succeeded in killing Devon with a poisoned potato.
* OutOfCharacterAlert: Lisa becomes suspicious of "Bart" when he starts acting and speaking in a refined manner.
* PrinceAndPauper: Bart and Simon. This is then PlayedForLaughs when an older man who looks like Bart as an adult shows up at the bathroom and shows them he's married to [[Rule63 a woman...who looks like Milhouse]].
* TheResenter: Simon says his half-siblings Devon and Queenly resent him because their father left their mother to marry Simon's.
* SpoiledBrat: Queenly is upset for being given a car that isn't the same one she wanted and rants that it was her worst Martin Luther King day ever.
* WeWantOurJerkBack: Albeit Lisa was reluctant to admit it to Simon.
* WouldHitAGirl: When Lisa hit Simon, she told him Bart would have hit her back in retaliation.
* WouldntHitAGirl: It came as a shock to Simon that Bart would. Well less the hit a girl and more throw his sister out of a window.
* YoungestChildWins: Mr. Burns is his parents' youngest child and inherited their fortune because his siblings had premature deaths.