Fan Casting Creepy Circus Music in Sort by Tropes

Done straight, it lets everyone within earshot know that they are in a world of fun for children of all ages! However, unless you're in an actual circus, then you are more likely to hear this kind of music slowed way down and played in a minor key. The effect is haunting, scary and maybe even sad and nostalgic. Often it will sound as if it's being played on an old, rusty calliope with wheezing pipes and unsteady pressure regulation, leading to out-of-tune notes.