The trunks of cars are mainly used for stashing items that take up too much space in the cab of the vehicle. In fiction, generally, the trunks will be used for storing people, alive or dead. This can be for several reasons:
The person in the trunk is alive, trapped in the trunk, and being taken somewhere by some villain.
The person in the trunk is alive, and is hiding in the trunk to follow whoever is driving the car.
The person in the trunk is alive, and is being taken somewhere willingly, riding in the trunk to hide from authorities who might stop the car.
The person in the trunk is dead, and the driver may or may not have put the person in there.
In the Cowboy Bebop episode, "Mushroom Samba", Edward stows away in the trunk of a bounty hunter's car so she can get into town and obtain some food.
As it turns out, the police don't take well to finding an unconscious child in the trunk of a car during a routine check. Even when she's just asleep and crawls away during the ensuing ruckus.
On Speed Racer, Sprattle and Chim-Chim would often hide in the trunk of the Mach 5.
In the Birds of Prey series, Lady Shiva is presumed dead after being attacked by the assassin Cheshire. In reality Shiva was simply knocked out and kidnapped, and Catwoman ends up finding her bound and gagged in the trunk of Cheshire's car.
In Superman #13, "Superman vs. The Archer", the ten-year-old Jimmy Olsen hides in Lois' trunk to follow her when she checks up on a scoop. He ends up saving her when the Archer kills her informant and tries to shoot her as well.
Subverted twice in the X-Men graphic novel "God Loves Man Kills." Tracking some villains surveying the mansion, Kitty Pryde uses her phasing powers to sneak into their car's trunk. Unfortunately, the trunk has sensors that detect her presence, and they activate knockout gas. Later, they try to execute her while the trunk is still closed, only to find the trunk empty, as she only inhaled a portion of the gas and retained enough consciousness to escape.
Miho from Sin City snuck into a mob enforcer's trunk while the car was still moving. Dwight was in the backseat along with some of the mob thugs as a Batman-Gambit to get them to cofess to a hit before killing them. Apparently, Miho could hear the conversation going on and killed one on command byb shoving her Absurdly Sharp Blade through the trunk and into the guy's skull.
X-23 was smuggled to Martin Sutter's house by Zander Rice in the trunk of his car when he decided to eliminate Sutter and his entire family after gaining full control of the X-23 project. It should be noted that Rice was dropping Sutter off at home at the same time.
In Kill Bill Volume 1, after killing O-Ren, The Bride stuffs Sofie into the trunk of her car. The Bride stops on a hill above a hospital, telling Sofie that she's only letting her live so she can tell Bill what she's done. She pulls Sofie out of the trunk and rolls her down the hill.
In Jackie Brown, a gun smuggler (played by Samuel L. Jackson) has one of his underlings (played by Chris Tucker) hide in his trunk, under the auspices of being ready for an ambush. He drives around the corner, pops the trunk, and shoots him twice.
In Reservoir Dogs, Mr. Blonde brings a kidnapped police officer to their hideout in the trunk of his car.
In From Dusk Till Dawn, the bank teller that the Gecko brothers took hostage can be seen in a cutaway of their stolen car's trunk, bound and gagged.
In Pulp Fiction, after Vincent shoots Marvin in the face in Jules's car, they eventually put his body in the trunk, clean up the blood and gore, then drive it to Monster Joe's Truck and Tow to be disappeared.
In Good Fellas, Billy Batts is put in the trunk after the trio of VillainProtagonists believe they've killed him and are taking him off to bury him somewhere.
The Transporter has its protagonist Frank Martin coming across a woman in his trunk (played by Shu Qi) upon breaking one of his rules (don't look in the package), which sets up the main plot of fighting a human trafficking scheme that we ultimately learn is being headed by the woman's own father.
When two policeman find this out, Frank knocks them out and locks them in the trunk. They're later killed when a bomb blows up his car.
Sin City - After Miho kills Jackie and his friends, the girls of Old Town have to dispose of the bodies and fast because Jackie was a hero cop. Dwight offers to dispose of the bodies in the nearby tar pits. The car Gail gets doesn't have a big enough trunk, so most of the bodies are chopped up to fit, and Jackie gets to ride shotgun with his head barely still attached.
Analyze This: near the beginning, the scene where the psychiatrist crashes into the mafia car, popping the trunk open.
In the sequel, Robert De Niro's character gets a job as a used-car salesman and uses the number of bodies a given car's trunk could hold as a selling point.
The Hangover - a pissed off naked Asian guy pops out of the trunk when the dudes search it.
The Villain Protagonist Donnelly in the short film China Lake has a thing for putting his victims inside the trunks of their own cars.
In Bad Boys II, Lowrey and Burnett forget they drive a suspect KKK member in their trunk. He starts to thrash about when the protagonists are being admonished by their captain for their last mess-up.
Captain: Running people over is not enough for you? Now you're into kidnapping?
The Green Hornet Strikes Again!: Kato uses this at one point when he needs to get to the villain's lair du jour, and the Hornet already drove off with the Black Beauty.
In Blues Brothers 2000, Elwood gets two Russian gangsters drunk and then stuffs them in the trunk of the BluesMobile.
In Thunderbolt And Lightfoot, two of the robbers hide in the huge trunk of a 1950s automobile in order to sneak them into a Drive-In Theater. Unfortunately the trunk is shut on the Badass Longcoat worn by one of the robbers; the man selling tickets notices it sticking out of the trunk and calls the police.
In Get Carter, the woman who seduced Carter's niece and persuaded her to star in porn movies is locked in the boot of his car by Carter, while he contemplates her fate. The car is then stolen by small-time hoods he has beaten up, who get even by pushing it into the River Tyne to spite him...
This backfires in Year of the Gun, where a kidnap victim (apparently a willing participant due to his left wing views) is put in the trunk only to die of carbon monoxide poisoning from an exhaust leak. The Red Brigades then pretend he'd been executed as an act of terrorism.
This also backfires in The Evil That Men Do. When they open the trunk the kidnap victim is dead, because the trunk was shot full of holes while making their getaway.
In American Gods, the bodies of the children that disappear in Lakeside are hidden in the trunk of the klunker, a ruined car put on the ice of the frozen lake each year. When the ice breaks, the dead child becomes a sacrifice to help the town stay prosperous.
In the Sookie Stackhouse book Club Dead, Sookie throws a weakened Bill in the trunk of a borrowed car to keep him out of the sun.
In Tea With The Black Dragon by R. A. MacAvoy, the protagonist is abducted and driven somewhere in the trunk of a car.
In The Fuller Memorandum, Bob gets abducted by cultists and stuffed into the trunk of a car, prompting him to give a slightly incoherent rant about how all how cars should be required to have transparent trunks.
Burke often hides one of his friends (Max the Silent, or the Prof armed with a shotgun) in his car's large trunk when going to a meeting with potentially dangerous dudes.
Live Action TV
In 24's second season, when Kim Bauer and her boyfriend Miguel are taking Megan to Kim's aunt's house, using Megan's father's stolen car, she is pulled over for speeding. The cop opens the trunk, which contains the corpse of Megan's mother.
In season 3 of Dexter, someone ambushes Dexter in the parking-garage as he's leaving work, ties him up and throws him in a trunk before driving off with him. Dexter - and the viewer - naturally assumes that it's the resident antagonist, The Skinner, taking him off to torture and murder, and Dex tensely frees himself of his constrains and readies himself to pounce the moment the trunk is opened - and so he does, squarely hitting... one of his colleagues, who'd chosen this rather melodramatic way to cart him off to a secret Bachelor-party. The rest of his colleagues are both impressed and amused by the reaction, and Dex rapidly recovers his cool.
Touched by an Angel - The Celebrity of the Week (Jack Ritter, if memory serves correctly) gets carjacked and stuffed in the trunk; after the car gets abandoned on the side of the road, the rest of the episode is a race against time to find him before he bakes to death.
On NYPD Blue a random car got in an accident with the car Andy & Bobby were in; they heard thumping & screaming from the trunk, which they popped to discover he had a woman in the trunk of his car.
Shane kidnaps JD in this way in Harper's Island, wrongly assuming that JD murdered Kelly.
Team Westen of Burn Notice often transports captured enemies this way.
In one episode of NCIS, the Creep of the Week is holding a navy officer for ransom, keeping her in the trunk of a car. This leads to a race against time to find her, as said Creep didn't know she had asthma (and therefore was in danger of suffocation before his deadline would come).
In Eureka, Fargo tries to fob his AI car Tabitha off on Larry, who refuses to accept her. Tabitha is self-aware and insulted enough to pursue both of them, lock them in her trunk, and drive around for a while until they're convinced she's going to kill them. She eventually lets Fargo go so he can save the town, though.
In Malcolm in the Middle, when Malcolm and Reese realized that Francis decided to give a concert ticket to a girl he just met instead of either of them, the two decided to sabotage his date. The final act of sabotage managed to work out after Francis's car got pulled over by a cop and the cop finding the two stuffed themselves in the trunk of the car.
When Will works as a car salesman in an episode of The Fresh Prince of Bel-Air, he has trouble selling a car to a group of Wiseguys until he shows them how well he fits in the trunk.
In The Sarah Connor Chronicles, Sarah is tied up in the backseat of a car being driven by Cromartie. When she frees her feet and jumps out, he simply stops, picks her up and throws her in the trunk.
Nick Knight from Forever Knight obtained a vintage car explicitly to invoke this trope if he is caught away from shelter at dawn.
In The Sentinel episode "Girl Next Door", Blair rescues a woman who's been trapped in her trunk by her ex. Unfortunately she turns out to be a criminal who winds up dragging Blair—at gunpoint—into an armed robbery and a drug-smuggling operation. At the end of the episode, he takes satisfaction in stashing her back in the trunk.
In the first season finale of Life, Charlie Crews abducts the man who committed the murders for which he was wrongfully convicted and spends several hours driving around L.A. with the man in the trunk of his car. Amazingly, the abductee manages to survive with only a few cuts and scrapes when the car is T-boned so hard that it flips over and lands upside down.
The Professionals. Doyle is put in a trunk by the bad guys for later disposal, only for the car to be stolen by joyriding hoodlums. He eventually gets himself free and the car gets driven off the road for no apparent reason. No-one was harmed though as there were only a couple of crash test dummies in the front seat.
For most of the pilot episode of The Americans the Jennings' Oldsmobile has a Soviet defector in the trunk.
The music video for Kanye West's song "Flashing Lights" has himself locked up in the trunk of a model's car where she brutally murders him with a shovel.
"Goodbye Earl" by the Dixie Chicks is about a woman who (with help from her friend from high school) kills her abusive ex-husband by poisoning his food. She then disposes of his body down by the lake, and puts the body in the trunk to facilitate this.
Taken very literally in an early AFI video, with a literal punk in the trunk who is taken someplace and stabbed to death. Yep, nice.
The Tragically Hip song Locked In The Trunk Of A Car, which is pretty self-explanatory. It's actually a dramatization of an incident in which a group of Quebec separatist terrorists took a government official hostage and stuffed him in the trunk of a car after knocking him out. He was later killed.
This trope makes up the chorus of "Trunk" by Spinout: "Get in the trunk, bitch, I'm gonna drive"
In the music video for And We Danced, a group of people going to the drive-in movie theater shove a friend in the trunk of the car, to sneak him in.
In the music video for Song Ji Eun's song "Going Crazy," the main character is seen driving along an abandoned road while periodically checking the trunk of her car. A Trunk Shot at the climax of the song reveals a kidnapped guy she has tied up in there, along with a gas can, which she douses him with before walking away and throwing a lighter behind her as the video cuts to black.
On WWE Raw Kane and Triple H were in a feud (the ever popular Katie Vick angle), and at the end of the episode Kane tossed Trip into a car's trunk and drove off - but then we saw the car trunk pop open just as they were going to black! Oops. Dealt with at the top of the next episode:
Triple H: I've got a special guest gonna come out here later - but before we come to that, I'd like to give a little personal message to Kane. Kane, this is just advice, but next time you try to accost somebody by sticking them into the trunk of a car, you should try to make sure that the trunk does not have one of those child safety latches on the roof - I mean, you can just pull it and jump OUT of the trunk before the person even drives off. Just a bit of advice.
Stand Up Comedy
The Cheech And Chong routine "Pedro and the Man at the Drive-In" (on the Los Cochinos album) is about smuggling someone into the drive-in in the trunk, and then being unable to get the trunk open.
In Assassins Creed II, when Desmond and Lucy are escaping from Abstergo, they make it to the parking garage. Lucy has Desmond hide in her car's trunk on the way to the safehouse.
In the first game, after killing Ben Goodman, Damon Gant stuffed the body in the trunk of Edgeworth's car.
In Investigations 2, a pair of kidnappers stash their live victim in a large box thrown into the trunk of a taxi.
In Apollo Justice, Pal Meraktis wanted to do this with what he thought was Alita Tialia's dead body, so he could dispose of it. He couldn't get his car started though (unbeknownst to him, someone shoved a pair of panties in the exhaust pipe), he settles for shoving her in the back of the next-door mobile noodle stand. This all bites him bad when it turns out Alita wasn't actually dead, and shoots him not long after coming to.
The aptly named "Dead Skunk In The Trunk" mission in Grand Theft Auto III has you drive a car with a dead mobster in the trunk while his "family" chases you.
In the first mission of the Russian campaign of Empire Earth, Grigor starts out hiding from the authorities in the trunk of his friend's Pyotr car and planning to escape Voronezh. However, he is aware that the trunk is "the first place the guards check" and thus they look for a better vehicle to smuggle him out. If they try to use the original car, they are caught and laugh at how Grigor tried to escape hiding in a trunk "like in a bad spy movie".
Reservoir Dogs has a driving mission where Mr Blonde is driving the cop he kidnapped back to the meeting point. If the player slows down for a certain amount of time the cop jumps out and flees.
Given its nature as a gangland simulator, no matter how wacky, Saints Row 2 features this in one of its missions. In the Brotherhood mission "Bank Error In Your Favor," The Boss, starting his Roaring Rampage of Revenge over the death of Carlos, finds out that Jessica, the one who ordered Carlos dragged to death, is isolated at a bank. They kidnap Jessica, stuff her in the trunk of her own car, and drive to a demolition derby where the car is parked in a line of cars for Jessica's boyfriend Maero, the Brotherhood's leader, to destroy with his monster truck. She ends up crushed to death and Maero founds out too late how and why when the Boss throws him the keys to Jessica's car.
Subverted in L.A. Noire, in an early case you find the bloody remains of a missing man in the trunk of an abandoned car. During the investigation, you learn that he butchered a pig in there to fake his own death and run away with his mistress. Played straight later, when thugs try to jam Jack Kelso in one, only for him to escape.
In the Phoenix Wright Musical Project, during the song "The Way Things Were", Wendy Oldbag snaps at Gumshoe "Oh what would you know, you disrespectful punk? Back in my day, you talked like that and we'd lock you in a trunk!"
In the episode "Don't Make Me Over", in a cutaway gag, Neil Armstrong runs into someone after filming the moon landing. The man wonders why he is on Earth, because just saw the moon landing on TV. Neil Armstrong kills the man with his astronaut's helmet and stuffs him into the trunk of his car.
In the episode "8 Simple Rules for Buying My Teenage Daughter", Stewie knocks out his babysitter's boyfriend, because he is jealous of him. He throws him in the trunk of Brian's car. Weeks later, he completely forgets about him.
In an episode of King of the Hill, Hank, Dale, and Kahn are in Mexico, trying to cross the border to the US, in order to escape a fine that they were sentenced to pay. Dale says that if the Border Patrol sees Hank and himself, they will be fine, but Kahn will get them arrested if he is seen. Kahn hides in the car's trunk, but gets out of it after Dale freaks out at the border crossing.
The two get thrown in the trunk themselves on at least two occasions: By Todd in "Canned", and by Muddy in the film.
In "A Great Day", the two stumble upon a man who is stuffing a dead body in his trunk, who promptly pays them to go away and not say anything about it.
In one episode of The Simpsons, Bart suddenly gets a phone call while driving,
Homer: Bart, I don't want to alarm you, but I'm inside the trunk. (Thumps come from the back of the car.) Homer: That was me. Some very uncool people put me here.
This happened to so often in the GDR that its border guards were taught a good method to immediately find out if there was someone hiding in a car's trunk: As a person is usually heavier than normal luggage, the car will be pushed down by the springs on its rear, and this pushes the front up. So, if the car's headlights shine up at any higher angle than they are supposed to, there is someone hiding in its back.
Parodied by those Halloween decorations that consist of a disembodied plastic hand with a hook that attaches to the inside of the trunk so it looks like someone's hand is hanging out.
According to one story this troper heard, if you are locked in the trunk of a car, it's possible to push out the rear lights/indicators and stick your arm out to attract attention and not suffocate/cook yourself. Depending on the model of the car, you'd likely need to remove a screw or nut to unfasten it first.
At least some models of cars now come with a cord to pull, which causes the trunk to spring open.