noun. A person or thing that is completely devoid of any use to society. Like a fish with a bicycle, a ghost ashtray has no benefit whatsoever, it merely takes up space and collects dust. Think about it, if a ghost could physically manipulate material objects, items like ashtrays and urinals would be completely useless to them. The term originates from a story about an evil, ambitious man who did alot of horrible deeds and killed many innocent people in a quest for more power. After he finally died, all spirits of the people he had wronged swarmed him. They squished and moulded his spirit into the shape of an ashtray permanantly.
Paris Hilton is such a ghost ashtray.