AceShowbiz - In anticipation of the premiere of "Joker: Folie a Deux", Lady GaGa appeared on "Jimmy Kimmel Live!" to perform "Happy Mistake", a song from the film's soundtrack. "Happy Mistake" is one of two original songs written for GaGa's character, Harlequin. She co-wrote the emotive track with producer BloodPop, explaining that it reflects on her artistic journey and the darkness that has healed her.

"I feel like throughout my music and all of the art that I've made - and with all of you - that has always been 'portraits of a broken girl,' " GaGa said. "Playing a broken girl has been something that has not always served me well. This idea that darkness feels like it heals me was something really important to my character, so I wrote 'Happy Mistake' as a reflection on, and celebration of, all the darkness that has healed me before, and all the dual identities I've carried."

GaGa also discussed the album "Harlequin", a companion piece to "Joker: Folie a Deux". The LP features covers of jazz standards, such as "I've Got The World on a String" and "Get Happy". GaGa emphasized that it is not the film's soundtrack but a "concept record" that can be experienced independently.

"It's just like an extension of the world," she said. "I wanted to do something with the music that's in the movie, but really bend genre and make it really hard to define, like my character. I think women are really exciting, complex, and can't be pinned down, so that's what Harlequin is."

During the interview, GaGa shared an "unorthodox" way that her fiance Michael Polansky proposed to her. While rock climbing, Polansky asked GaGa if he could propose, to which she replied, "Yes! It's okay."

"He had the ring in his backpack, so it was so super cute. He like got into his backpack and pulled it out," GaGa recalled. "I'm a modern lady, and I liked what he did. I guess you have to do something unorthodox like that."

"Joker: Folie a Deux", starring GaGa and Joaquin Phoenix, will be released in theaters on October 4.