Joaquin Phoenix’s Singing Made Lady Gaga ‘Spit Up’ Her Coffee

Lady Gaga had quite a strong reaction to hearing her Joker: Folie À Deux co-star Joaquin Phoenix sing for the first time.

Phoenix, who stars as the Joker/Arthur Fleck in the musical sequel and its predecessor Joker, revealed the music legend's reaction to his vocals in a recent interview with Empire.

"I do seem to remember her spitting up coffee... so that felt good, that was exciting, and made me feel confident," he shared.

The actor revealed more about his musical partnership with the Grammy Award-winning singer and seasoned performer, who plays Lee/Harley Quinn in the film.

"Gaga was always very encouraging of just, 'go with what you feel, it’s fine.' For somebody who’s not a performer in that way, it can be... uncomfortable to do that, but also very exciting," Phoenix said.

READ MORE: 'Joker 2' Trailer Teases a Full-Blown Musical Sequel

The second film starring Phoenix as the Joker sees the infamous villain in the Arkham institution awaiting trial, where he meets Harley Quinn.

In this iteration of the story, music plays a very important role in the doomed couple's relationship.

"It was important to protect that with poor phrasing and occasional bum notes," Phoenix explained of getting into character.

"Arthur grew up hearing his mother play these songs on the radio. He’s not a singer, and he shouldn’t sound like a professional singer. He should sound like somebody that’s taking a shower and just bursts out into song," he continued.

Gaga also did an interview with the outlet and unveiled what it was like to prepare for the role of Harley Quinn.

"People know me by my stage name, Lady Gaga, right? That’s me as that performer, but that is not what this movie is. I'm playing a character, so I worked a lot on the way that I sang to come from Lee, and to not come from me as a performer," she shared.

She revealed that she had to separate herself as a performer from her character, down to even the finer details like the way she breathed.

"It was unlike anything I’ve ever done before. I’m a trained singer, right? So even my breathing was different when I sang as Lee," she said.