When something big, loud, shaky, or forceful happens, we may hear car alarms going off outside or offscreen to indicate the magnitude of this event. If it's really big, it'll set off all the car alarms in the area.
Loud sounds can indeed shake a car enough to set off the alarm, making this Truth in Television.
Not to be confused with extreme damage to a car, although sometimes they overlap where the extreme damage also causes the car alarm to go off.
Not to be confused with The Alleged Car, which is a car with unreliable building qualities or bad safety features.
- In the 2008 The Incredible Hulk movie this happens during the fight between the Hulk and the Abomination.
- Cloverfield: the first sign of the monster is a tremor causing car alarms to go off.
- In Iron Man 2 a couple of car alarms go off as Iron Man and War Machine fly noisily through a parking lot; half a second later Ivan Vanko's air capable Hammer Drones pass through making even more noise, setting almost all the cars off.
- In Tremors, the Gummers' SUV is destroyed by a Graboid after its burrowing disturbs the ground underneath the vehicle and sets off its car alarm.
- Those poor bikes in Mystery Team.
- In Highlander the first quickening sets off several car alarms.
- The Iron Giant has the rare case of the horn going off due to direct contact with the vehicle. Basically, the Iron Giant, when he and Hogarth discover the junkyard that Dean works at, starts eating everything in there. It then eats a car... which hadn't had its horn removed yet, causing it to go off.
- Pacific Rim makes a running gag out of this, as at least one car alarm gets set off more or less every single time a kaiju or jaeger steps on a road.
- Spider-Man 2: Peter Parker loses his powers and attempts to jump to another building to see if he got them back and at first it looks like he's going to make it. But he doesn't and falls on top of a car. He then slowly gets back up and waddles away trying to support himself on another car and activates the alarm by barely touching it.
- Film/2012: The tremor and fissure opening at the supermarket causes many car alarms to go off.
- In a rare literature example, in Animorphs Jake sent Marco to cause a disturbance and every car had a car alarm. Really, really much funnier in text.
- Harry Turtledove's The Case of the Toxic Spelldump creates a Magitek version, the sylphs that power magic carpets are supposed to scream if the carpet is stolen. Instead, they scream incessantly at the slightest provocation. (Just like real car alarms.)
- In the Torchwood episode "Exit Wounds", the city wide bombing of Cardiff by Capt. John Hart sets off these. Later in Children of Earth: "Day One" when the government blows up the Hub this happens.
- In the third season finale of Criminal Minds, the episode ends with nearby car alarms blaring after an SUV explodes. The catch? One of the main characters (the audience is not told who until the season 4 premiere) is about to get into the SUV when it explodes.
- Top Gear (UK):
- In the second US special, Clarkson and Hammond set off a whole line of parked cars in Vegas by revving the engines of their muscle cars as loudly as possible. Unfortunately for them, this quickly drew the attention of the local authorities.
- In the India special, Clarkson makes a massive homebrewed firework which he plans to shoot off at a party. When he does, it ends up being so strong that it sets off more than a dozen car alarms.
- One episode of Pimp My Ride featured one car whose alarm could not stop going off.
- Supernatural. In "Mommy Dearest" Castiel does this while wiping out a diner full of demons with a blast of light.
- Power Rangers Samurai: Clash of the Red Rangers: When the Grinders attack a highway bridge, the carnage causes this. The first glimpse of Scott is his gloved hand reaching in and turning the alarm off.
- Exploited on Monk. A woman supposedly jumps to her death and lands on her lover's car, setting off the alarm. He's a teacher who's busy proctoring an exam at that moment. He actually murdered her and left her body in a position that she would fall onto his car during the exam. He knew the alarm would establish an alibi for her death.
- At one point in the Video Game Awards 2011 exclusive trailer for Metal Gear Rising: Revengeance, Raiden kicks an enemy soldier into a parked black car hard enough to set off the car alarm and nearly flips it over. Raiden then remarks shortly afterwards "too easy!" before cutting him up.
- If a stationary vehicle gets clipped by a stray bullet in Freedom Fighters (2003), the alarm will go off. Two or three more, and it explodes.
- Left 4 Dead includes cars on some maps with active alarms that will go off if shot (with convenient flashing lights to let you tell them apart from the safe alarmless cars). Since the game takes place in the middle of a Zombie Apocalypse, setting one off is very bad news. And heaven help you if you have a Griefer on your team, because if you do, they're all gonna go off.
- Discussed in "Why obnoxiously loud car alarms aren't as common today" from the YouTube channel Cheddar. It explains why car alarms used to be sensitive enough to cause this trope, and aren't as sensitive nowadays.
- Dragon ShortZ: The end of the first episode, "Two Saiyans and a Baby" has Vegeta fire a Galick Gun at a fleeing Nappa who snapped a pic of Vegeta acting quite nice towards his son. The beam fires out the front door of Capsule Corp and rattles a car, causing its alarm to go off.... and wake Baby Trunks, who had just been laid down to sleep about a minute ago.
- Anyone with an aftermarket car stereo knows how easy it is to set off entire blocks just by driving down the street with the bass turned up.
- Some cars have exhausts loud enough to set off car alarms when they rev. Here's an example.
- Ditto loud claps of thunder.
- And fireworks.
- Whenever there's an earthquake, it doesn't have to be a huge one, just one that slightly shakes the house enough to make dishes fall.
- Older car alarms were notorious for being extremely sensitive to motion/touch.
- Go to a Civil War Reenactment, and wait for the cannons to start firing. You will suddenly hear a dozen honking, beeping anachronisms.
- Military bases tend to have large ceremonies involving cannon fire for various occasions. It didn't take long for most bases to start issuing notices of said ceremonies and asking everyone to disable their alarms before the ceremony was scheduled to begin.
- Less triumphant than the previous examples, but marching band competitions tend to do this, especially if the competitors are heavy on the percussion.
- Airshows involving military aircraft with afterburners will almost certainly result in a few cars wailing nearby.
- Particularly common offenders were any American aircraft designed with the capacity to climb to 40,000 feet at the speed of now. It's not uncommon for entire parking lots to go off when an F-15 or F-22 rockets off the runway due to the very loud engines rattling everything in the area. About the only aircraft that won't do this is the A-10... However this is a feature, not a bug.
- Several car alarms were set off by the Chelyabinsk meteor explosion in 2013 as can be seen here.