Bart's in Jail!

Abe Simpson receives an urgent phone call telling him that Bart is in jail and that he needs to get $10,000 to the "authorities" or Bart will face a massive prison sentence. Because Grandpa not-unreasonably finds the notion of Bart being in jail to be plausible and also because he wants to help his grandson, he does wire the money, only to realize that he was the victim of a scam. Everyone but Homer feels bad for Abe and consoles him with their own stories of being scammed.

When Homer learns that Abe lost his $10,000 and that the money was planned as an inheritance for himself, he gets so angry that he keeps mocking and yelling at Abe at length. Marge, Lisa and Bart finally get him to stop treating Abe so badly over an honest mistake after Homer gets scammed himself and they all go over to the retirement home so Homer can apologize—and they are all there when another scammer calls in to try the same "(Person) In Jail" scam by using Lisa's name.

Lisa then gets an idea that involves Abe using his talent of having the world's longest and most aimless conversations to keep the scammers talking until Lisa can use advanced computer software to pinpoint their location to a building in Shelbyville. The family heads there and finds out the place is a troll farm whose callers are not criminal masterminds but simply very downtrodden people working a bad job for minimum-wage (Moe Szyslak works there, for one thing). Chief Wiggum and his fellow police officers break up the ring, but Marge wonders if they really did any good considering how corrupt the entire world is.

Homer and even Lisa then decide to take a huge stack of gift cards for their own usage, and Marge briefly succumbs to her dismay when she partakes of some ill-gotten free items at 'Zerz restaurant (spurred on by a nasty dream visit from Loki alongside other tricksters Anansi, Monkey King, Jesus Christ, Huēhuecoyōtl, and Bill Cipher from Gravity Falls).

Later on, Marge decides she will not let herself become that cynical, and gives a woman asking for $20 to buy gas (her "credit card isn't working") the money and her address to send it back. Some time later, Marge does get the money back in the post, and her faith in humanity is restored—as it is revealed that Abe actually sent her the letter and the money, because he did not want to see Marge's spirit be ruined by the evil of scams around the world.

Originally, at the end of the episode, it was revealed that Grampa had been cheating at cribbage for years to get the money that was taken by the scammer.[4] The producers reached out to Neil Gaiman for visual inspiration of Loki. Gaiman suggested they use Arthur Rackham's "Rhinemaidens" picture for inspiration.[5]

Casting

Alex Hirsch reprise the voice of Bill Cipher

Bill Cipher is once again voiced by Gravity Falls creator Alex Hirsch, Cipher yells, "Buy crypto, suckers!" The unexpected cameo surprised both fans of The Simpsons and Gravity Falls, who flocked to social media to discuss the crossover. Bill's reference to cryptocurrency is believed to be a homage to the character's most iconic lines in Gravity Falls. "Remember: reality is an illusion. The universe is a hologram. Buy gold. Bye!" The chaotic, universe hopping monster is one of the show's more notable villains, tormenting protagonists Dipper Pines, Mabel Pines and Grunkle Stan.

Addressing the crossover on Twitter, Alex Hirsch wrote, "From age 8-18 I didn’t miss a single Simpsons premiere. I read the guide until the pages fell out, memorized every line, knew the writer of each ep & could tell you the season by the size of the characters pupils. I’m in total disbelief that tonight I just did a cameo on the show." Hirsch continued on to say, "If tonight I get hit by 3 busses then lightning then fall out of a window into a truckload of mousetraps I’ll die happy. Thank you @TheSimpsons for inspiring me to get into animation in the first place & for this surreal honor."[6]

• Bart's in Jail! at IMDb