It seems that Joaquin Phoenix lived up to his Joker: Folie à Deux character's name on set.

Joaquin Phoenix, no doubt a method actor, got into character once more on the set of Joker: Folie à Deux; some of his character’s antics even transitioned into real-life scenarios. Harry Lawtey, in a recent interview with Variety,

Folie à Deux, recalled the time he and Joaquin Phoenix played a trick on Lawtey’s mom on the movie set. Phoenix stayed in full Joker makeup on set, even when not filming, so Lawtey said the actor played a trick on his unsuspecting mom.

Folie à Deux” co-star Harry Lawtey told Variety that the Oscar winner couldn’t stop coughing after doing Arthur’s maniacal chuckle. “To watch him do that laugh and to see the effect on him — on everyone — blew my mind,