The Simpsons their advertising. As a promotion for "The Simpsons Movie", twelve 7-Eleven stores were transformed into Kwik-E-Marts and sold "The Simpsons" related products. These included "Buzz Cola", "Krusty-O" cereal, pink doughnuts with sprinkles, and "Squishees". In 2008 consumers around the world spent $750 million on merchandise related to "The Simpsons", with half of the amount originating from the United States. By 2009, 20th Century Fox had greatly increased merchandising efforts. On April 9, 2009, the United States Postal Service unveiled a series of five 44-cent stamps featuring Homer, Marge, Bart, Lisa and Maggie, to commemorate the show's twentieth anniversary. "The Simpsons"
The Simpsons Guy Appel then asked for permission from "Simpsons" executive producers Matt Groening, James L. Brooks and Al Jean to use their characters. This was approved; Appel was previously a writer-producer on "The Simpsons" for four seasons, and retained his former colleagues' trust. Dan Castellaneta, Julie Kavner, Nancy Cartwright, Yeardley Smith and Hank Azaria guest star as their "Simpsons" characters, but Harry Shearer, the final main cast member of "The Simpsons", was unavailable. Asked how he felt about the crossover, Shearer replied, "Matter and anti-matter." "Family Guy" writers pitched several storylines for the crossover, including one in which the Griffins stay with