At the end of the movie Mank (2020), holding clipboard with his hand, director Orson Welles visits his writer Mank's:
Orson Welles: Rise and shine, hombre. Shoot-out at the O.K. Corral. Before we buckle down, I gather you have something to get off your chest?
Why did Orson Welles say, "Shoot-out at the O.K. Corral"?