Gryffindor: If you open your eyes in a pitch-black room, the color you'll see is called eigengrau.

Ravenclaw: Space has a distinct smell: a bouquet of diesel fumes, gunpowder, and barbecue. It's mostly produced by dying stars.

Hufflepuff: In the 1870s, a Belgian village attempted to train a fleet of 37 official mail cats to deliver letters. They failed.

Slytherin: In Iceland, a government committee prevents parents from giving babies names it deems too weird. The committee's name is Mannanafnanefnd.