This is a story I heard from a friend who heard it from a friend who heard it from a friend etc etc etc. A family return home to find a giant hole in thier roof, their dog dead on the floor and litres of urine all over the place. Completeley bewildered they call the police who are also baffled. Only later do they realize what had happened. Suppposedly a jet was flying overhead and ejected the contents of it's toilet accidentally (I think they can only do it over oceans), it froze in the cold atmosphere, crashed through thier roof killing their dog. The ice melted and thus explains the mystery. the guy I heard this off swears it's true...Make up your own mind.
The part about the dog isn't true, but the part about airline toilet material falling from the sky is. It was reported on television, with pictures of the hole in the roof, the reporter's description of the smell, etc. It happened in the Seattle metro area some time since 1991.