What is a curio shop?

A curio is "A curious or unusual object of art or piece of bric-a-brac." A curio shop then is by extension a shop that sells curiOS. They're often seen in movies as having disturbing/incredibly out of the ordinary objects, but most curio shops simply have interesting or unusual things.

Also note that apparently there is a curio shop in Webkinz (as the last answerer noted), but in the real world, the above is what a curio shop is.