written for the character by Kudrow with Adam Chase, Betsy Borns and Chrissie Hynde. The song was conceived in 1995 by Borns, a Friends writer who originally intended for its lyrics to be about a pungent dog entitled "Smelly Dog". Having a tendency to incorporate aspects of her personal life into Friends episodes, Borns initially based the song on a malodorous dog she had once owned named Gouda (named after the cheese), at first penning it "as an ode to her childhood pet", before ultimately deciding a song about a foul-smelling cat would be more humorous. Chase, another writer on Friends, also contributed lyrics. Kudrow composed the melody herself, as she had done for all of her character's original songs. "Smelly Cat" first appears in the sixth episode of the second season, "The One with the Baby on the Bus" (1995), which Borns also wrote. Hynde (lead singer of rock band The Pretenders) guest stars in the episode as Stephanie Schiffer, a professional singer originally hired to replace Phoebe as Central Perk's resident musician, to whom Phoebe teaches "Smelly Cat" at the end of the episode. Hynde co-wrote the song's music with Kudrow. The musician had agreed to guest star on Friends with little knowledge as to how popular the relatively new sitcom had already become in the United States, having not heard of the show prior to being cast. Kudrow described writing with Hynde as "amazing". Critics believe Hynde's guest appearance bolstered sales of The Pretenders' cover of "Angel of the Morning", which Hynde also performs in the episode. "Smelly Cat" grew increasingly popular among fans of the show, who sent letters to producers asking that they release the song on an album. Upon realizing the song's popularity, Reprise Records' Howie Klein expressed interest in developing a concept album based around "Smelly Cat" as a follow-up to the previous years' Friends album, but Kudrow's participation in the project was undecided. An updated version of the song entitled "Smelly Cat Medley" was eventually released on the soundtrack album Friends Again (1999), credited to Phoebe Buffay and the Hairballs. The track is a combination of "Smelly Cat" excerpts from various episodes, featuring vocals from Kudrow and The Pretenders. Although the album's cover features all six of the show's main cast members – Kudrow, Jennifer Aniston, Courteney Cox, Matt LeBlanc, Matthew Perry and David Schwimmer – Kudrow was the only main cast