Turning the ignition when the car is already on!
If there were one sound that an evil villain could harness to defeat humanity, it would definitely be the sound that your car makes when you forget it’s already on, and you turn the ignition. Hearing that mix of deafening screeches for only one second is still enough time to scare the living motherfuck out of you.
I'm always concerned that my heart will quit on me when I absent-mindedly turn the ignition, and unleash this audible dragon. Because the sound the engine makes, which could be mistaken for a cat genocide, has the ability to make even nails on a chalkboard cringe.
Post-noise, you always have the appearance of that poor bastard who has "seen some things." Hands trembling, cold sweat, staring blankly out the windshield in shock and shit. This moment is the human equivalent of an electric collar shocking a dog for barking too loudly.
Note to self.. DO NOT under any circumstances turn the ignition while the car is already on. Failure to do so will result in sudden hearing loss in combination with waking the dead and shitting of pants.