The Simpsons, despite having consistently cartoonish elements and deep family values, is also full of genuinely dark and depressing gags.While some focus on the defeatist attitude of Springfield, others can carry some extremely dark baggage with them -- especially given the history of the Springfield residents. However, the series' darkest joke, which happened in Season 19's "Papa Don't Leech," is actually a reference to HBO's The Sopranos.

"Papa Don't Leech" opens with Homer and Abe Simpson driving on a dark night. Abe is at the wheel, and the two men bicker as they always do. Abe soon becomes distracted by switching the car's music and isn't paying attention to the road, which is when they encounter Patty and Selma driving the opposite way. The Simpsons' car is forced off the road and down a hill, crashing at the bottom. Although Homer is uninjured, Abe is badly hurt.

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Homer goes to call 911 -- until Abe points out that he'll require round the clock assistance and attention from Homer going forward. Homer closes his phone and quietly places his hand across Abe's mouth and nose. Abe's attempts to break free grow weaker and weaker until he dies. Homer then wakes up -- revealing to Lisa that he'd been having a "wonderful" dream and wistfully saying that he always wakes up before the good part.

Nominally, the moment is a reference to The Sopranos. In the HBO crime drama's sixth season, protagonist Tony Soprano finds himself in a similar situation as Homer and Abe with his drug-addicted "nephew" and potential criminal heir, Christopher Moltisanti. After multiple seasons of drama between the two, Christopher is badly injured in a car crash. Deciding he's had enough of him, Tony takes the opportunity to pinch Christopher's nostrils shut, suffocating him in the same way as Homer does Abe.

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It's a shockingly dark moment from Homer, but it also tracks with the cruel relationship he's long had with his father. Abe's casual cruelty and poverty -- only exasperated when Homer's mother left him -- left Homer with emotional scars that he's still dealing with. On the other hand, Homer has proven to be consistently neglectful to his father, even going so far as to abandon him on the operating table in Season 9's "Homer Simpson in: 'Kidney Trouble.'" While the two have been shown to love each other, they've also been portrayed as having a good deal of mutual contempt.

This moment takes that loathing to an extreme, however, with Homer admitting that he apparently has this dream repeatedly and doesn't consider the act of killing his father to be a nightmarish scenario. Instead, Homer sees this act as something pleasant. The rest of the episode -- which sees the return of Lurleen Lumpkin as well as a guest appearance by the Dixie Chicks -- doesn't make mention of the moment again. Still, this Sopranos reference is one of the most surprising and haunting moments from across the entire run of The Simpsons.

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