Joaquin Phoenix pulls epic prank on 'Joker: Folie à Deux' co-star's mom

Joaquin Phoenix pulled up a hilarious prank on his Joker: Folie à Deux co-star's mother.

In an interview with Variety magazine, Harry Lawtey, who plays Harvey Dent, shared a hilarious incident from the rehearsals.

Lawtey revealed that Phoenix, who was in his full Joker makeup "suggested, as a joke, that we FaceTime my mum and scare her."

The You & Me actor added, "My mum was in England, so it was quite late, and she was getting ready for bed. And I said, ‘Hello,’ and then I brought the phone up to my face, and Joaquin put his head on my shoulder."

"My mum screamed, ran away and woke up my dad," he hilariously said.

During the same interview, Lawtey also praised Phoenix's intense commitment to his role in the film, describing it as "a master class."

"To watch him do that laugh and to see the effect on him — on everyone — blew my mind. He would be coughing after each take. It was an education to watch him move through different flavors and shades of that performance," he said.

Joker: Folie à Deux, also starring Lady Gaga besides Phoenix and Lawtey, is scheduled to release on October 4.