The Oct. 18 broadcast of the show's annual "Treehouse of Horror" Halloween episode featured a spin on Stephen Sondheim's musical Sweeney Todd. The segment, titled "There's No Business Like Moe Business" was a stage performance of a musical concerning Homer Simpson's death and a specially-flavored microbrew served at Moe's Tavern. In less than seven minutes, the show managed to reference and skewer The Phantom of the Opera, homophobia and bad audience behavior.
The episode can be viewed here; "There's No Business" is the third segment, beginning at the 14:47 mark: