"Well, I know what I'm going to be showing him later. That's so cool, thanks for showing me that," the singer said.

Joaquin Phoenix's laugh in "Joker" is considered one of the most compelling cinematic moments. The 49-year-old won an Oscar for his role in Todd Phillips' 2019 drama, which has since gone down as a landmark piece of cinema.

Lady Gaga and Joaquin Phoenix were among the stars on had for the Joker: Folie a Deux premiere in Los Angeles Monday evening.