It's the best joke from a film almost springloaded with them, but what is the origin of Airplane!'s famous "Don't call me Shirley" gag? Airplane! was written and directed by Jerry Zucker, Jim Abrahams, and David Zucker, with the comedy being heavily inspired by the 1957 b-movie Zero Hour!, which featured Sterling Hayden (The Godfather). The plot of Zero Hour! featured a World War 2 pilot forced to land an airplane after the pilots become ill with food poisoning.
Zero Hour!'s combination of unintentionally hilarious dialogue and taking the silly events of the plot deathly serious made an impression on Zucker, Abrams, and Zucker, who retained a lot of the dialogue and key sequences from the movie in their script. Airplane! pioneered a new type of genre parody where the actors play the movie straight in spite of the ludicrous events unfolding around them. The filmmaking trio would perfect this type of comedy with 1984's Top Secret! starring Val Kilmer (Batman Forever) and The Naked Gun franchise.
The movie also relaunched the career of veteran actor Leslie Nielsen, who appeared in classics such as Forbidden Planet and The Poseidon Adventure. Airplane! cast Nielsen as Dr. Rumack, with his deadpan performance being the highlight of the movie. This is especially true of the movie's most famous joke, when Rumack brings troubled war pilot Ted Striker to the cockpit and reveals he'll have to fly the plane. Striker states "Surely you can't be serious?" to Rumack, who replies with “I am serious — and don’t call me Shirley.”
This joke has been oft repeated in the years since Airplane!'s release, making appearances in The Office and video game Call Of Duty 4: Modern Warfare. It turns out this joke has a simple origin, with the Zucker brothers and Abrahams revealing in a Vulture interview it was born out of their practice of watching old, serious b-movies with very dramatic dialogue and then crafting gags around them. In this case, they saw a movie where a character exclaims "Surely you can't be serious?" and inspiration struck when they added the now famous punchline.
While Airplane! was a huge success, the trio sat out the inevitable follow-up Airplane II: The Sequel. The sequel reunited most of the cast - excluding Leslie Nielsen - and took place on a space shuttle. Striker finds himself having to fly the shuttle too, and William Shatner (Star Trek) makes a surprise appearance as the commander of a lunar base. While the sequel isn't terrible, it tends to just repeat most of the original jokes to weaker effect, and the movie underperformed at the box-office, killing plans for Airplane III.
Airplane! has a lot of great jokes but "Don't call me Shirley" is easily the most quoted. It's doubtful the Zuckers and Abrahams realized how popular the line would become, and it has gone on to adorn t-shirts, memes, and even became the subtitle of the film's DVD release.