Slippers are shoes you wear indoors.

They are called slippers not, as you might expect, because they make you slip up and hurt yourself, but because they slip on, as opposed to having laces. The shoes that make you slip up and hurt yourself are called office shoes.

The reason people wear shoes is to stop their feet from becoming dirty and wet when they walk around outside. So why would anyone want to wear them inside? One can only assume that the carpets in their houses are also dirty and wet. Otherwise they would not wear slippers, but would walk around in their stockinged feet. Maybe it is the other way round, and their feet are fetid and smelly and they don't want to defile their carpets with the detritus. Who knows?

Teenage girls like the fluffy animal variant. This is, presumably, to go with all the stuffed animals they have, and their Robbie Williams posters.