When The Simpsons showrunner Al Jean learned of the Balenciaga collaboration, he first reaction was: "What’s Balenciaga?"

The New York Times

Balenciaga artistic director Demna Gvasalia first pitched the idea of a collaboration in an email to The Simpsons creator Matt Groening in April 2020. “I always loved the tongue-in-cheek humor, the romance and the charming naïveness of it," said Gvasalia of The Simpsons. When Jean learned of the project in January, he had to consult Wikipedia to learn about the fashion house. "His first pitch to Balenciaga had a similar framing to the one they ended up going with — Marge’s birthday wish — but diverged with Mr. Gvasalia’s character deciding that the brand’s next show would be held in Springfield," reports The New York Times' Jessica Testa. "When the Balenciaga plane lands there, its models aren’t allowed into the United States because they’re too thin and beautiful. Springfield’s residents become the models, their nuclear plant is the runway, and the ghost of Mr. Balenciaga makes an appearance. But Balenciaga preferred that Springfield be brought to Paris, Mr. Jean said. From there, the story was revised and tweaked — to the point that the writers joked about 'Draft 52 of the Balenciaga script' — up until two days before the Paris showing. Mr. Gvasalia made specific contributions to the script, Mr. Jean said. For example, the episode ends with Homer embracing and singing 'La Mer' to Marge on a post-show party boat on the Seine. But Mr. Gvasalia wanted one final joke, so he asked that Homer’s jacket be set on fire by a Frenchman smoking a cigar. Mr. Jean then suggested that Anna Wintour, who had appeared in the front row of the fashion show, try to put out the fire with expensive champagne, which Homer tries to drink instead." Wintour approved the use of her likeness, but declined to participate. “She said, ‘Please don’t have me do that,’ so it became Demna,” said Jean, adding:  “The animation crew, this is the hardest thing they’ve had to do since The Simpsons Movie."