When my father was a teenager, a friend of his father's was a fireman. In a professional building where they had put out a fire, they found a box with a skeleton that had been prepared for teaching purposes. While the fire wasn't hot enough to destroy the skeleton, it did ruin the mounting, discolor the bones, and render some of the smaller bones cracked and brittle.
The owners of the building didn't want the specimen since they didn't think it was fit for teaching anymore. The fireman - knowing that my father wanted to follow in my grandfather's footsteps and be a doctor - presented my my father with the still perfectly-good, hinged-jaw skull.
During the year, the skull sits in a discreet corner of the bookcase - people not expecting to find it are usually startled when they are looking through my parents' book collection. (As kids, we used to love to send unwary babysitters into the library just for that purpose.) At Halloween, the skull is an integral part of the presentation - it's usually in the middle of the pile of candy. Some kids are seriously freaked out by it, some are fascinated. Most everyone, though, does a double-take and is startled when they realize it's real.