Lightmare Fuel is when Nightmare Fuel is Played for Laughs or your genuine laughter is coming from the scariest of places. In short, it is the perfect combination of the truly scary with the truly funny. This often happens in comedy works, typically Black Comedy, but can just as often occur in horror stories.
A work of this nature will sit around the center of the Sliding Scale of Comedy and Horror.
- The Kurosagi Corpse Delivery Service. Most of the series features a lot of this trope. In the first book, one of their stories features a corpse made from parts of seven different girls who gets vengeance on her killer by telling him a joke. It drives him insane.
- Franken Fran, down to its core. It runs on gore and giving characters terrifying And I Must Scream scenarios, but it pretty much plays it all for dark laughs and caustic satire. It helps that those who get it the worst usually deserve it.
- Emo Phillips: "They say public speaking is the number-one fear in the country. I would've thought the number-one fear would be being Buried Alive... with a severed head. And just before your flashlight's battery dies, the eyes open. [Beat] But no, apparently it's the public speaking thing."
- Susie Essman once recounted how, after watching a scary movie, she searched her entire house for any conceivable place the villain could possibly he hiding (including her doll house) before finally turning off the lights, climbing into bed, and pulling the covers up to her chin, still too terrified to sleep because she keeps hearing this soft, rhythmic chirping noise that she can't identify... until she realizes that her nose is whistling.
- Ghostbusters. The Librarian scene. In the DVD commentary, Harold Ramis and Ivan Reitman stated that they achieved the perfect balance in that moment, with people in the audience during the first screening both laughing and screaming at the same time.
- An American Werewolf in London is seemingly made of this in some parts. Griffin Dunne and David Naughton are laughing it up, joking about the superstitious villagers as they walk along the moonlit road one second, and in the next second Dunne's throat is ripped out on-camera and Naughton is slowly bleeding out from a werewolf bite. Later, Dunne reappears as an increasingly-rotten corpse to confront Naughton, yet the duo can't help but revert to the same snarky buddy-buddy humor.
- "MacGoogles the Scottish Frog" in Max Keeble's Big Move. He is genuinely creepy-looking... and yet you won't be able to stop laughing.
- In the "musical comedy" version of Little Shop of Horrors, we go from laughing to cringing, especially once Seymour starts feeding Audrey II whole human beings.
- Shaun of the Dead: Once they finally get refuge in the local pub, they are quickly besieged by zombies. As Shaun and the others try to keep the zombies at bay with a rifle, Shaun's mother admits to Liz (Shaun's ex, although his mother isn't aware of the breakup) that she was bitten by a zombie earlier in the movie, dooming her to death and resurrection. She dies in Shaun's arms as he begs her not to leave him. This is followed by a genuinely tense Mexican standoff over what to do with Shaun's mother - David reckons they have to shoot her, Shaun and Ed are hysterically protective, Liz reluctantly sides with David (calling him a "twat" in the process) - which is punctuated with some of the movie's funniest dialogue.
- The final segment of Cat's Eye is something of a Stephen King primer for kids, combining King's penchant for horror elements from out of left field (the villain is a vicious little troll trying to suffocate a young girl in her sleep) and some amusing slapstick woven into an otherwise tense final confrontation with the heroic feline protagonist (who defeats the troll with a record playing The Police's "Every Breath You Take" at 78 RPM).
- In Jaws, the scene where Brody is complaining about having to dump chum (chopped up fish and fish blood) into the ocean begins with the line "Slow ahead. I can go slow ahead. Come on down here and chum some of this shit," and ends with the line "We're gonna need a bigger boat", having gone from funny to scary in a nanosecond when the shark abruptly appears.
- In Sleuth, the story jumps from funny to horrifying within a second. Some scenes you might alternate between smiling and being afraid for the characters' lives several times within one moment. You could even find yourself grinning while thinking "I think something horrible is going to happen any minute".
- The 1989 comedy The 'Burbs on the surface seems to be a wacky "mistaken identity" comedy about three childish protagonists who suspect that their next-door neighbors are a family of serial killers. The protagonists' wives, of course, think they're just being stupid. Wacky hijinks fill the rest of the movie, until the protagonists discover that the the trunk of the next-door neighbors' car is filled with decomposed human remains. Because the neighbors really are a family of serial killers.
- There are more than a few moments of this in Beetlejuice.
- Gremlins. The little monsters are hilarious... until they start killing people in messy, messy ways...and sometimes still are then.
- Zombieland. The explanation of Rules #1 ("Cardio") and #2 ("Double Tap") are accompanied by a visual of people being graphically attacked and killed by zombies. They are hilarious and tragic and scary all at the same time.
- The various "zombie kills" (especially the "Zombie Kill of the Week").
- Abbott and Costello Meet Frankenstein, equal parts Monster Mash horror and screwball comedy. The Universal Horror monsters (including Dracula, the Frankenstein monster, the Wolf Man, and a brain-swapping mad scientist) are real and played quite straight, but they're balanced out by Abbott and Costello's wisecracking antics.
- BrainDead is a textbook example of this, since the amount of gore and horror is so ludicrous mixed with dumb humor that it's pretty damn funny. A notable example is Lionel finding his mother ate Paquita's dog:
- Sam Raimi films drift back and forth along the Sliding Scale of Comedy and Horror, and sometimes folds the scale in half, mashing both ends together. The Evil Dead (1981) started with doses of Lightmare, Evil Dead 2 increased both Horror and Comedy, Army of Darkness slid to slapstick extreme, the Drag Me to Hell snapped to the other extreme but added a few tension-breakers.
- The scene where Ash's room starts laughing at him is probably one of the best examples of this trope in cinema. It's disturbing to watch this demonic force tormenting a likable protagonist, and to watch his sanity fraying at the seams as he starts laughing along with everyone else, and yet, at the same time, it's hard not to laugh with him thanks not only to the ludicrously over-the-top carnage he's had to deal with over the past 24 hours, but also the hilariously cartoonish voices (especially that Porky Pig-sounding lamp) and the goofy special effects. Then it swings back to disturbing when Campbell's genuinely infectious laughter gives way to believably agonized howls of fear and exhaustion, and when he frantically blasts at something on the other side of the wall, not knowing what's waiting for him on the other side, that it's genuinely terrifying again. Sweet lord.
- Any Discworld novel involving the Things From The Dungeon Dimensions, or similar Lovecraft Lite monstrosities, will make it clear they're a serious and disturbing threat and, at the same time, completely ridiculous, often making the point that a creature seemingly made of the bits left over once everything else was created is probably going to fall over a lot.
- Charlie and the Chocolate Factory enters this territory when Augustus Gloop falls into the chocolate river, gets sucked up a pipe, and is subsequently faced with the threat of being turned into fudge. From then on, what started as just another light Comic Fantasy for kids is in Black Comedy territory as the other Hate Sink brats receive similarly wacky-creepy comeuppances. While the sequel Charlie and the Great Glass Elevator plays its threats more seriously, with potential victims given a bit more sympathy, it still has a lot of this trope: for example, Willy Wonka taunting a carnivorous alien who tried and failed to deliver the elevator a Literal Ass-Kicking with a song about its now-swollen rump.
- H.P. Lovecraft's short story "The Statement of Randolph Carter" reads as a fairly typical example of the author's Cosmic Horror oeuvre, right up until the last line, when instead of his friend Warren, Carter hears a hideous unearthly voice speaking on other end of their radio line from the depths of a foul and monstrous pit: "You fool, Warren is DEAD!"
- Doctor Who has been doing this for longer than most series could dream of. Granted, it also dishes out plenty of outright Comedy (all flavours), Ham and Cheese and high octane Nightmare Fuel, as well. Being able to do all of this at once, though? It's an art, which individual writers occasionally get horribly wrong. But, when it goes right, it goes very right indeed. Douglas Adams's run is still held up as the benchmark for getting Lightmare Fuel right, for all it was going on before he pitched up and has continued since. For just cause, however.
- Being Human (both versions) constantly whips between wacky sitcom hijinks and extremely gory supernatural horror, which can be more than a little jarring.
- American Horror Story: Murder House has a moment of this. In one episode, Hayden, Ben's former mistress and student, discovers where he lives and threatens to reveal to Ben's pregnant wife that she is pregnant with her and Ben's love child from the affair. When Ben agrees to go someplace with her to discuss the pregnancy, Harvey comes out of the blue and hits her dead in the face with a shovel. Upon realizing that she's not dead, he hits her again.
- Red Dwarf wouldn't be what it is without its capacity to make you both laugh and shudder. Often at the same time: the Polymorph, anybody? More Teeth than the Osmond Family... masquerading as a pair of increasingly tight boxers. And, that's just one instance. If the Ending Theme doesn't convince you after that, nothing will.
- The universe of Warhammer 40,000 is a cruel and unforgiving one, with madmen given power to burn everything they see as heretical, daemons invading worlds through the nightmares of the psychic, where merely surviving to adulthood is an accomplishment... Unless you're the Orks, in which case the universe is a permanent excuse to fight, get drunk, shoot impossibly cool guns and drive really fast without caring where you're going. Where other armybooks get lurid descriptions of the slaughter caused by daemonic incursions or waking up tomb worlds, Orks get things like defeating daemon princes with a defiant gesture involving a power claw and the daemon's groin, or a Waaagh travelling back in time and (possibly) defeating itself. Orks have it made.
- Stand Still, Stay Silent: This comes packed with hilarious, top-quality character interplay... that just happens to have a threat or two skulking quietly undercover if you pause to think. We know for certain the utterly gorgeous scenery definitely has oodles of horror just waiting to pounce, even while we're up to our eyeballs in such wonderful things as kitties and sawblade-trains, too. And, when you do see the Nightmare Fuel and its frenetic action and/or creeping dread either played for drama or, you guessed it, comedy (often at the same time), it's timed to knock your socks off with a barrage of complicated feels before ducking back under the cover of character-based comedy. Yup: if this work doesn't count, nothing does.
- Homestar Runner has Marshie and Senor Cardgage, characters who radiate nightmare fuel played entirely for laughs.
- Quite a few articles from the SCP Foundation are simultaneously somewhat scary and hilarious.
- SCP-426: I am a toaster that can only be spoken of in the first person. My entire article is consequently written in this manner, which leads to a great deal of amusement. However, prolonged exposure to me also has some... unpleasant side-effects, leading my previous owners to, be respectively, electrocuted attempting to eat an electrical socket, eating so much bread their stomach exploded, dying of blood loss after attempting [REDACTED] with me, and finally, to suffer from malnutrition after inserting two slices of bread and waiting for them to pop.
- SCP-914's experiment log, in between straight-up funny.
Input: 1 lb. raw ground beef
Setting: Very Fine
Output: [DATA EXPUNGED]. Appeared to be [DATA EXPUNGED] ██████████ started mooing ██████████ bitten subject [DATA EXPUNGED] ██████████ escaped into ██████████ screaming ██████████ [DATA EXPUNGED] hungry for [DATA EXPUNGED]. Subject immediately terminated.
- Similarly, 447. It's perfectly safe as long as it doesn't come into contact with dead bodies. It's a good lubricant, salad dressing and improves gasoline efficiency as long as doesn't come into contact with dead bodies. It seems to be entirely benevolent but must never come into contact with dead bodies.
- SCP-1839, a book about fish that causes readers to begin to think they are fish as long as they read it and either hold their breaths while in air, or try to breathe underwater, causing them to drown. Note that this will not happen to you as you are a fish.
- SCP-1545, a two-person llama suit that causes the wearers to continue playing their characters until their deaths. If the back dies, the front continues to walk around and play the act. If the front dies, the back will keep dancing.
- This trope is partly the reason why Buzzfeed Unsolved is so popular. Disturbing murders and haunted places are interspersed with a lot of comedy, often at the genuinely scary situation's expense.
- Cracked would like you to know that Spiders Are Scary.
- The Mr. Bucket episode of Board James. A genuinely creepy story, played completely straight, about a man being stalked through his own home by a deranged rapist... and said rapist just happens to be a candy-colored children's board game, cheerfully singing in a Simpleton Voice. You won't know whether to laugh or scream!
- The Amazing World of Gumball dips into this frequently. The best example of this is "The Joy" where a Zombie Apocalypse virus is played completely straight, even though said virus makes everyone puke rainbows and act ridiculously happy.
- Courage the Cowardly Dog is pretty much made of this, being a genuinely creepy cartoon played for absurdity.
- The Marvelous Misadventures of Flapjack is prone to bouts of some seriously scary imagery that's played entirely for laughs.
- The Ren & Stimpy Show was all about this, at least up until John K. was kicked out from it. The episodes produced by Games Animations also stepped in the territory of Nightmare Fuel frequently - however, with these, it was unintentional and more prone to be genuinely horrifying rather than just used for comedic effect.
- The Simpsons' Treehouse of Horror episodes can dip into this. Many of them manage to be genuinely creepy while still having all the hallmarks of the show's humor.
- In South Park, pretty much anything that gives the audience Nightmare Fuel will also end up making them laugh at the same time such as Kenny's multiple deaths, and Cartman making Scott Tenorman eat his own parents.
- My Little Pony: Friendship is Magic is known to use this trope occasionally. If the show's Nightmare Fuel page is anything to go by, it might be overshooting.
- Gravity Falls had traces of this in it's first season, went full force in the second. The highlight being Bill Cipher, a genuinely sinister Omnicidal Maniac who, when he manages to take over the world, treats it all like it's one big party.
- Archer loves this. Highlights include Malory casually killing the ISIS cleaning lady staff in "The Rock" by sabotaging the lift to collapse, Ray bloodily losing his hand in "Pocket Listing", and just about any scene involving Kreiger, an Affably Evil Mad Scientist.