2.6. Bob and Carol and Ted and Alice all live in the same house. Bob and Carol go out to a movie, and when they return, Alice is lying dead on the floor in a puddle of water and glass. It is obvious that Ted killed her but Ted is not prosecuted or severely punished. (From How Come?)
2.6 answer: Alice is a goldfish; Ted is a cat. (Or a dog, since the fish's body is still there rather than eaten.)
2.6a. A very common variant uses the names Romeo and Juliet instead, to further mislead audiences. For example: Romeo is looking down on Juliet's dead body, which is on the floor surrounded by water and broken glass. (AC)
2.6a answer: Same.
2.6b. Minor variant: Tom and Jean lay dead in a puddle of water with broken pieces of glass and a baseball nearby.
2.6b answer: Tom and Jean are both fish; it was a baseball, rather than a cat, that broke their tank. (from Mike Reymond)