Timothée Chalamet and Robert Downey Jr. are already excited for what could become one of the biggest box office showdowns of the year.During a recent Q&A moderated by Downey for Chalamet’s upcoming film Marty Supreme, the two stars revealed that their highly anticipated blockbusters, Avengers: Doomsday and Dune: Part Three, are set to hit theaters on the same day this December. The coincidence inspired them to coin a new pop culture term: “Dunesday.”“We both have films opening on December 18, and we decided to coin it — we’re thinking Dunesday,” Downey told the audience on Thursday Jan. 15.He further added, “We’ll see if we’re still friends by then.”Downey is returning to the Marvel Cinematic Universe in Avengers: Doomsday, marking the first Avengers film since 2019’s Avengers: Endgame. This time, the actor steps into the role of iconic villain Victor Von Doom, also known as Doctor Doom. While Marvel has yet to reveal Downey’s full look, the film has already released multiple trailers teasing the return of several fan-favorite characters across the Avengers, X-Men and Fantastic Four franchises.Meanwhile, Chalamet will reprise his Dune role as Paul Atredes for Dune: Part Three, an adaptation of author Frank Herbert’s 1969 novel of the same name. The film also stars Zendaya, Jason Momoa, Josh Brolin, Florence Pugh, Rebecca Ferguson and Anya Taylor-Joy and Robert Pattinson.The dual release immediately sparked comparisons to the “Barbenheimer” phenomenon of July 2023, when Barbie and Oppenheimer dominated the box office after debuting on the same day.