Number XX is a song sung by the cast from the "There's No Business Like Moe Business" segment of "Treehouse of Horror XX". Although the music is credited to Alf Clausen, it is actually set to the Theme Song, which was written by Danny Elfman. The lyrics were written by Daniel Chun.

Lyrics[]
- Cast:
- We hope you've enjoyed this year's Halloween episode:
- Treehouse of Horror Number 20!
- (The roman numeral XX drops down on the main cast.)
- Kodos:
- Shhhhh!
- (points to Kang, who is sleeping)
Trivia[]
- Kodos saying "Shhhh!" at the end is a reference to the Gracie Films logo after the end credits on all episodes.