The 44-year-old actor is enjoying huge success with his titular role as the Batman villain in Todd Phillips' dark take on the origin tale, which has taken box offices worldwide by storm.
Joaquin started his movie theatre tour by stopping at the Universal Studios AMC for a 4 P.M. IMAX screening, before heading to downtown Los Angeles and the Alamo Drafthouse Theatre, where he popped up after the end credits of multiple screenings.
At one such screening, Joaquin was fielding questions from cinemagoers when one pleaded with him to "do the laugh" - referring to the Joker's maniacal half-laugh, half-cry, which the actor admitted took him an age to perfect.
But while Joaquin appeared a good sport in answering other questions from fans inside the cinema, he seemed less willing to grant that request, insisting to the man, "I can't do it. You do it - I wanna see you do it!"
As the fan hit back that "I'll do it if you do it," the screen star still refused, giggling awkwardly before telling the crowd, "Anyway, I hope you have a good weekend. Thank you guys for coming out - I do appreciate you supporting the movie."