executive producer Bill Oakley's idea and included live action directed by David Mirkin. "Treehouse of Horror XX" included the segment "There's No Business Like Moe Business", which was the first to be musically themed. Traditions Opening sequence Every Treehouse of Horror episode opens with a special introductory segment. The first, second, and fifth Treehouse of Horror episodes open with Marge standing on a stage and warning parents about the content of the episode, advising them to put their children to bed. The warning in the first episode was put in as a sincere effort to warn young viewers, as the producers felt it was somewhat scary. The entire segment was a parody of Edward Van Sloan's pre-credits warning from the 1931 film Frankenstein. Marge's warnings quickly became a burden to write, particularly because – as she herself noted – they were mostly ignored, so after "Treehouse of Horror V", they were dropped. The segment returned in the season 31 episode "Thanksgiving of Horror". Other Treehouse of Horror episodes have opened with parodies; for example, "Treehouse of Horror III" had Homer introduce the episode in a manner similar to Alfred Hitchcock in Alfred Hitchcock Presents, "Treehouse of Horror IV" had Bart introduce the episode and segments in a manner similar to Night Gallery, and "Treehouse of Horror V" featured a parody of The Outer Limits. The sixth and seventh episodes featured short clips with no lines because the episodes had run long, and longer segments were cut. Following "Treehouse of Horror VII", the opening has been upwards of a minute long and sometimes featured an introduction by a character, such as Mr. Burns in "Treehouse of Horror XVII" or included over-the-top violence, such as "Treehouse of Horror VIII" (which showed a Fox Network censor being brutally murdered) and "Treehouse of Horror XIV" (which showed the Simpson family killing each other). In the opening segment of the first five episodes, the camera zooms through a cemetery where tombstones with humorous epitaphs can be seen. These messages include the names of canceled shows from the previous season, deceased celebrities such as Walt Disney and Jim Morrison, and a tombstone with an inscription that read "TV violence" that was riddled with bullets as the camera panned on it. They were last used in "Treehouse of Horror V", which included a solitary tombstone with the words "Amusing Tombstones" to signal this. The tombstone gags were