Los Angeles, Jan. 15 -- Hollywood may have found its next tongue-in-cheek cinematic event, when Robert Downey Jr. and Timothee Chalamet have playfully proposed turning December 18 into a pop-culture phenomenon, as "Avengers: Doomsday" and "Dune: Part Three" prepare to open in cinemas on the same day.

The actors appeared on stage together in LA on Wednesday for a special screening of Chalamet's A24 movie Marty Supreme.

Downey Jr. told the audience: "We both have films opening on December 18, and we decided to coin it . We're thinking Dunesday.'" The moniker got a laugh in the room, with Downey Jr. adding: "We'll see if we're still friends by then."The idea is that the two blockbusters can give each other a leg-up so that they can later bas...