Everyone loves a good surprise! Well, almost everyone. Audiences definitely do, particularly when it comes to horror movies. Some of the most memorable moments in horror history were completely unplanned, either improvised by the cast at just the right time or carefully (and stealthily) orchestrated by select crew members for maximum impact. The best reaction, after all, is usually an honest one, and if you're going for scares, there's really no better way than the sneak attack. The same is true of laughs, which often tend to overlap in the genre.

Here we have the best of the best, some of the most iconic improvised moments in horror movie history. Whether they make you laugh, feel nostalgic, or jump out of your skin, they've left an indelible mark on film history and pop culture.

Ed Cheers Shaun Up In Shaun Of The Dead

Horror comedies are exactly the type of film that lend themselves to the possibility of unscripted moments, with comedic minds frequently finding new bits and funnier line deliveries while in the heat of the moment. Edgar Wright already had a Western comedy called "A Fistful of Fingers" and multiple television credits, including the cult hit "Spaced," under his belt before he exploded in popularity with 2004's "Shaun of the Dead." The film was the first installment in his "Three Flavours Cornetto" trilogy (or "Blood and Ice Cream" trilogy, depending on who you ask), which was followed by "Hot Fuzz" and "The World's End." All three scripts were written by Edgar Wright in collaboration with trilogy star Simon Pegg, who plays the titular character in the ultimate zombie bromance film.

After Shaun is dumped by his longtime girlfriend Liz (Kate Ashfield), he meets up with his best friend Ed (Nick Frost) at The Winchester, their favorite bar, in an attempt to cheer him up. As the two throw back pints, Ed begins making up backstories for all of the "rich, interesting characters" that frequent The Winchester. At one point, he sees a woman dressed in conservative, academic attire and spouts, "Ooh! C**k-a-cidal maniac. She's an ex-porn star. She's done it all…"

Turns out, this line was not in the script, but actually an improvisational comment from Frost. The actress in question was the mother of Edgar Wright's girlfriend at the time, and knowing Wright wanted a natural laugh out of Simon, gave Frost free range to come up with new lines to try and elicit the perfect reaction. Well, it looks like calling her a "c**k-a-cidal maniac" did the trick. (BJ Colangelo)

The Chestburster From Alien

The chestburster sequence in Ridley Scott's 1979 sci-fi horror masterpiece "Alien" is one of the most shocking moments in movie history, and that's in large part because the cast's reaction to the horrific event is genuine. In the scene, John Hurt's character has become infected by a face-hugging alien, which impregnated him with a baby xenomorph. No one on the ship knows this yet, however, and they're all shocked when he doubles over during mealtime and then begins to seize. As they try to restrain him, the baby alien shoves its head through his ribcage.

The only actor completely in on the whole thing was Hurt because he had to go through special effects prep and set-up. The rest of the cast, however, was kept in the dark beyond the fact that something would come out of his chest. They didn't know what it would look like or how it would happen, and they definitely didn't know that real animal organs and gallons of fake blood were going to be shot out in their direction. The screams, gasps, and horrified faces of the cast are all very real, which sells the shock of the scene in a truly visceral way.

While the cast was clearly surprised by the fountain of blood and guts that sprayed their way, they did at least have a bit of warning that things might get messy. When they arrived on set that day, they noticed that the cameras were covered in plastic and the crew were all wearing raincoats. Clearly, there was going to be some kind of splash zone, but after a false start with only a tiny bit of blood and a not-too-threatening burster, the actors let down their guard. That's when Scott struck and made truly terrifying movie magic. (Danielle Ryan)

Phone Assault From Scream (1996)

When Wes Craven's slice-and-dice game-changer "Scream" hit the scene in 1996, it shook up the old slasher movie conventions of the decade prior with its acerbic approach to all of the rules, from its non-virginal final girl Sidney Prescott (Neve Campbell) to its hip-to-the-genre teens, who threw the barbed insults of screenwriter and "Dawson's Creek" creator Kevin Williamson as their peers became cannon fodder, one by one. One of the film's funnier moments comes amid the chaos of the climax; on the "Scream" blu-ray commentary, Williamson states that the character of Stu Macher was "underwritten," but it was no problem for Matthew Lillard, who ad-libbed several of Stu's lines throughout the runtime.

Williamson explains that Stu (played by Matthew Lillard) and Billy Loomis (Skeet Ulrich) have revealed to Sidney that they're behind the spree of killings, but she slips away, calling to taunt Billy on the phone from elsewhere in the house. At this point, Ulrich is supposed to rage-throw the phone at the nearby kitchen countertop but because of the slippery theatrical blood covering his hands, the handset goes rogue and lands squarely on Matthew Lillard's head, prompting the ad-libbed but hilariously slurred in-character response: "You f***ing hit me with the phone, dick!"

It's a great moment of levity in the eye of the storm, sweetened further by the satisfaction of seeing Sidney dispatch two psychopaths with little more than household items just moments later. Keep an eye out for references to both killers in the year's latest, mega-meta installment of the franchise, the poorly-titled "Scream" (2022). (Anya Stanley)

'Here's Johnny!' From The Shining

There are quite a few scary moments in the 1980 Stanley Kubrick movie "The Shining," but the vast majority of them are in the script. Kubrick was an exacting director who pushed his performers to the limit, even when it hurt them, so it's surprising that he allowed an improvised line in one of his films. Kubrick required dozens of takes for every scene, and that sheer amount of repetition led to one of the greatest improvised lines in cinematic history.

During the climax of the film, writer-gone-mad Jack Torrance (played by Jack Nicholson) is chasing his wife Wendy (played by Shelley Duvall) around the empty Overlook Hotel. She locks herself in a bathroom and he hacks his way through the door with a hatchet before peering in through the hole. Nicholson plays the part as completely unhinged, and he taunts Wendy as he attacks the door, growling "little pig, little pig, let me in" like the Big Bad Wolf of fairy tale legend. When he manages to cut through enough to reveal his face, he sticks his head into the hole in the broken wood and shouts "Here's Johnny!"

The line was improvised, referencing late-night talk show host Johnny Carson, who would be introduced the same way every night by co-host Ed McMahon. It was an easy-to-catch reference for Americans in 1980 that makes the film feel more lived-in and of this world despite its supernatural story. The quote has gone on to be referenced far more from "The Shining" than its original usage on "The Tonight Show," and it's all because of Nicholson's need to change things up after so many takes. (Danielle Ryan)

Meeting Dr. Hannibal Lecter From Silence Of The Lambs

Sir Anthony Hopkins only spends 24 minutes of "Silence of the Lambs" on screen, but his gripping performance as Hannibal Lecter earned him an Academy Award and has made him one of the most recognizable figures in horror history. Playing a brilliant forensic psychiatrist who also happens to be a serial killing cannibal is enough to creep out audiences, but Hopkins made the character his own, providing multiple unscripted moments that helped make the film so memorable.

When Lecter delivers his famous "I ate his liver with some fava beans and a nice chianti" line, he follows up with an inhaled breath slurping sound, one that was not in the script. As Hopkins tells it, it was an odd sound he was making on set and figured it would be a creepy addition to his already unsettling line. However, one of his greatest unscripted contributions didn't require any sound at all.

When Clarice Starling (Jodie Foster) first encounters Dr. Lecter from his cell, Ted Tally's script describes the moment as "Dr. Hannibal Lecter is lounging on his bunk, in white pajamas, reading an Italian Vogue." On-screen, however, Hannibal Lecter is standing in the middle of the cell, staring directly at her with a curious expression on his face. In an interview between Hopkins and Foster as part of Variety's "Actors on Actors" series, Hopkins shared that it was his decision. "I said, 'I'd like to be standing there, I can smell her coming down the corridor,'" he confessed.

"Silence of the Lambs" would still have been a controversial success, but Hopkins' unscripted moments continue to stand the test of time. (BJ Colangelo)

'You're Gonna Need A Bigger Boat' From Jaws

One of cinema's most iconic lines (no, really) was actually a cheeky in-joke among its film crew. Steven Spielberg's 1975 adaptation of Peter Benchley's novel "Jaws" sees its principals — Amityville police chief Martin Brody (Roy Scheider), oceanographer Matt Hooper (Richard Dreyfuss), and seasoned shark hunter Quint (Robert Shaw) — in pursuit of a great white shark responsible several attacks in the area. Having found said shark, an absolute unit that later takes the pithy fishing vessel down with ease, Brody delivers the line with gravity to the ship's captain: "You're gonna need a bigger boat."

Don't call it an ad-lib, though. Carl Gottlieb, both a co-writer of the adapted screenplay and bit actor in the film (as reporter Ben Meadows), told The Hollywood Reporter that production on the set of "Jaws" was notoriously stingy, with producers Richard Zanuck and David Brown overloading the boat and crew to such exasperation that "You're gonna need a bigger boat" became a go-to catchphrase behind the scenes for everything from a delayed lunch to technical issues — any situation that finds its people poorly equipped for the mission.

While the line was unscripted, Roy Scheider infused the haggard crew's frustration into the story, sprinkling the phrase into his performance as it seemed fit; the one that stuck (after Brody gets within chomping distance of the beast for the first time) is the one that lives on the big screen today and in the mouths of anyone woefully unprepared for the task before them. (Anya Stanley)

'Jesus Wept' From Hellraiser

The last line in a movie has a tendency to stick around in audiences' minds long after the credits roll, but few have quite the staying power as the final line in Clive Barker's 1987 horror film "Hellraiser." When the movie's hero, Kirsty (played by Ashley Laurence), manages to outsmart her devious uncle Frank (played by Sean Chapman, Oliver Smith, and Andrew Robinson) and send him back to hell, courtesy of the demonic Cenobites. Chains with hooks begin to impale his body and pull him in all directions, ripping his flesh in a way that's truly horrible to look at. When his skin can stretch no further, he delivers one final line before being yanked apart: "Jesus wept."

In the original script, Frank was supposed to look at Kirsty and say "f*** you," angry with her for condemning him to eternal damnation and suffering once more. Robinson was allegedly not a fan of swearing, however, and wanted to change the line to something a little less vulgar. He opted for "Jesus wept," which is both a line from the Bible and a phrase used to express exasperation. The line has a kind of fun double meaning because Frank could either be making a serious Biblical reference about loss and pain, or he could just be letting out a little frustration with the whole situation.

Barker found the ad-lib to be brilliant and ended up using it for the finished film. It's a perfect ending, combining pitch-black humor and abject horror to create something totally unique. There are plenty of fun stories about actors ad-libbing clean versions of lines for censored television versions, but it's pretty rare that one makes it into the theatrical cut. (Danielle Ryan)

Nada's Most Memorable Line From They Live

"Rowdy" Roddy Piper (real name Roderick George Toombs) was one of the greatest professional wrestlers in history, with fellow WWE Hall of Famer Ric Flair describing Piper as "the most gifted entertainer in the history of professional wrestling" upon his induction in 2005. Before John Cena and Dwayne "The Rock" Johnson proved that wrestlers could be bonafide Hollywood superstars, wrestlers weren't often known for their acting chops. The biggest exception, however, was Roddy Piper. He had a recurring role as a dangerous wrestler named "Da' Maniac" on "It's Always Sunny in Philadelphia," and starred as Sam Hell in the cult hit "Hell Comes to Frogtown." His biggest cinematic claim to fame, however, is starring as Nada in John Carpenter's masterpiece, "They Live." As Nada realizes that Earth has been taken over by aliens that are hiding in plain sight to manipulate the masses, he goes on a crusade to free humanity from their mind control.

Nada is the ultimate everyman if the ultimate everyman was also a talented professional wrestler who could easily fight Keith David for nearly six minutes straight and dish out clever and cutting insults to formaldehyde-faced aliens. In the film's most memorable moment, Nada enters a bank with a gun and delivers the line, "I have come here to chew bubblegum and kick ass … and I'm all out of bubblegum." It has since become a pop culture staple, with people who've never even seen "They Live" knowing the reference. The line was later famously referenced in the video game "Duke Nukem" and became a popular meme for newer generations.

Incredibly, the line was improvised by Roddy Piper and was not a part of John Carpenter's original script. Sooner or later, everybody pays the Piper! (BJ Colangelo)

'Game Over, Man!' From Aliens

In space, no one can hear a rage-quit.

When people quote James Cameron's 1986 sci-fi action classic "Aliens," the line that comes up the most often is a desperate one. Stranded on a desolate, hostile moon teeming with acid-blooded xenomorphs who mean to cocoon, impregnate, and otherwise slaughter all humans on sight, Colonial Marine and fan favorite Private Hudson (played by the late Bill Paxton) surveys the situation and utters the iconic line, "That's it, man! Game over, man! It's game over!"

Cameron, who had previously helmed "The Terminator" and knew a thing or two about memorable but doomed characters, encouraged the sizeable cast of "Aliens" to develop backstories for the people they play. Some actors had enough experience to handle that individual worldbuilding, but for Paxton, who only had a few (still formidable) film credits to his name at the time, the task proved daunting. That said, Paxton could see his character's jumpy, less-than-mature demeanor and decided that Hudson was, like many service members, an avid gamer, prone to hysterics when he fails to overcome the combat simulators he and his fellow Marines train on.

What better syntax to capture utter defeat than the near-universal "Game over?" The phrase was a pop culture grenade, good enough for the Jigsaw killer to repeat when a victim failed to pass his survival tests in James Wan's "Saw" and its numerous sequels, nearly two decades after "Aliens" hit box office gold. For his performance, Paxton earned a Saturn Award for Best Supporting Actor and the undying devotion of horror fans worldwide. (Anya Stanley)

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