Every so often, a horror movie comes along with a scene so disturbing it becomes a permanent part of our cultural consciousness. There was the shower scene in “Psycho”, the horrifying “Exorcist” head spin, and the moment when an all too giddy Jack Nicholson gave us his scariest Ed McMahon impression. However, the bloodiest of the bunch is without a doubt the infamous “chestburster” scene from “Alien”.

We all know how the scene goes down. When the crew of the commercial spaceship “Nostromo” receives a mysterious distress call, the team heads to a nearby planet to check for survivors. Unfortunately for Kane, the Executive Officer (played by John Hurt), he ends up on the wrong side of a “facehugger,” a nasty alien that latches onto his face and impregnates the poor guy with a murderous parasite. Eventually, the facehugger detaches itself, and we’re lulled into a false sense of security when Kane shows up in the “Nostromo’s” dining room, shaken but seemingly okay. The crew carries on with their meal, everyone is laughing and enjoying themselves…and then something horrible rips out of Kane’s chest.

According to “Alien” lore, when the film was screened in Dallas, Texas, the chestburster had moviegoers jumping out of their seats, scrambling down the aisles, and running for the restrooms. Of course, audience members weren’t the only ones disgusted by “Alien’s” extraterrestrial gore. Believe it or not, the cast was completely caught off guard by all that blood, but before we can talk about one of cinema’s greatest practical jokes, we have to flash back to the time when Dan O’Bannon came down with food poisoning.

The story goes that screenwriter Dan O’Bannon was munching on some fast food when he took a bite out of a really bad burger. During the night, he woke up with a painful case of food poisoning and was forced to call an ambulance. As the paramedics rushed O’Bannon to the hospital, his imagination went wild, and he pictured a monster thrashing inside his innards. And as it so happens, writer Ron Shusett (who received story credit on “Alien”) was toying with the idea of a creature that impregnates humans through their mouths. When O’Bannon and Shusett got together, their ideas melded into one horrifying screenplay.

When it finally came time to shoot the scene, director Ridley Scott ordered most of the cast to leave the set. He didn’t want the actors to see the creature until the moment it tore out of John Hurt’s body. Scott wanted to shock the cast and capture their genuine reactions. Of course, they knew something was going to pop out of Kane’s chest—they’d read the screenplay—but the script simply said, “This thing emerges.” They didn’t really know how it would work or what it would look like.

John Hurt, of course, knew exactly what was going to happen. He was the guy sprawled across the table, after all. Well, sort of. Hurt was actually sitting in a deck chair with head poking up through the table. His “body” was a prosthetic chest, and the special effects team filled it full of organs purchased from a nearby butcher shop. In addition to all the kidneys and livers, two technicians were lurking under the table with a compressed blood machine, ready to unleash six gallons of red liquid onto the set.

When the cast finally returned, they were greeted by an unsettling sight. All four cameras were wrapped in plastic, and the crewmembers were sporting raincoats. Only when the alien tried to rip through Hurt’s fake chest, the puppet couldn’t make it through the T-shirt. As the special effects team cut the cloth ever-so-slightly, the actors moved in closer, their fears temporarily allayed. And that’s when the “exit wound” erupted, courtesy of a few tiny explosives, and the chestburster made its grand appearance.

Organs and fake blood splattered all over the set. In fact, there was so much gore that Ridley Scott had to tone it down in post-production. And according to plan, the cast’s reactions of shock and horror were completely real. One burst of blood shot straight into Veronica Cartwright’s face (she plays Lambert, the “Nostromo’s” navigator), and she was so surprised that she actually fell over backwards while cameras were still rolling. When Ridley Scott called cut, Yaphet Kotto (the actor who played Parker, the Chief Engineer) was so troubled that he retired to his room and refused to speak to anyone. The director’s master prank had worked, and thanks to Dan O’Bannon’s hamburger, John Hurt’s acting skills, and some amazing special effects, the Alien burst out of Kane’s chest and into cinematic history.