Digger uses distinctive fonts for characters, resulting in a certain race speaking in “strange, scary fonts”. The creepy skin lizards are actually quite nice, but the protagonists don’t know that initially.
As if that wasn't enough to establish it as Hell Is That Noise to the characters, then came "[S] Equius: Seek the highb100d". After you enter the vent as Nepeta, it's dark, you have no idea where Gamzee is, and all the music stops save for... this. And you can hear the honking.
The honking also turns out to be the noise Lord English made to announce his birth into the universe. And his sole purpose for existing is to ensure a universe's destruction.
What, no mention for the way the "tangle buddies" song in Jade: Wake up slowly devolves into this demonic, pitchy version of the lyrics, preceded by this steadily increasing low whirring as horrorterrors flash at the screen? I mean, sure, they're actually out to help the main characters, but that doesn't make it any less disturbing the first time you watch the flash.
Sluggy Freelance: Anyone who survives the demon’s spawn (a litter of kittens) will forever jump at the sound of "mew."
Awful Hospital: The bow tie delivery guy has a voice described as "as if a hundred birthday clowns got together to strangle each other to death at the same time, and every last one of them liked it." It's implied to have somehow made a living circulatory system throw up.