The Pokémon series has a history of morbid touches beneath its "cute" exterior. There's Cubone, a Pokémon who wears the skull of its dead mother, and Yamask, who carries around a mask of its face when it used to be human. But my favorite is Lavender Town, the main graveyard of the Pokémon world.
It's where the player encounters ghost Pokémon... and incredibly creepy soundtrack:
This song, composed by Junichi Masuda, was rumored to be the cause of hundreds of child suicides across Japan shortly after the original Pokémon games were released in 1996, known as "Lavender Town Syndrome" or "Lavender Town Tone." This was apparently due to a high-frequency sound in the song that could only be heard by undeveloped ears--hence why it was only happening to kids. This sound drove the children to kill themselves. It was quickly changed by Nintendo for the game's worldwide release, so the only place the sound can be found today is in the original Japanese Red and Green versions of Pokémon.
Whether the story is true or not is questionable. Either way, it's one of the freakiest songs ever featured in a children's video game.