Ahead of time, prepare the cups that are described below. Have everyone sit in a circle. Pass out the paper and pencils and explain the guessing game. Then shut out the lights and start the story. You have to have the room dark so that people cannot see what's inside of the cups. The guests write down what they think is really in the cup. You'll want to briefly turn the lights on between each cup so that they can write their answers down. If the kids are really young (they can't write), then simply have each one guess what it is out load (but don't tell them what is really in the cups until the very end).
"Once in this town there lived a man named Hal O. Ween. T'was years ago this very night that he was murdered out of spite. They say these are his remains.
Here is his brain, which now feels no pain. (a wet squishy tomato)
Here are his eyes, still frozen with surprise. (two frozen peeled grapes or olives)
Here is his heart. Be careful lest it start! (a large lump of uncooked liver)
Now we have his hair, which once was so fair! (a handful of corn silk or wet fur or yarn)
Feel these drops of his blood. All the rest turned to mud. (a little catsup thinned with warm water)
One hand all alone, just rotting flesh and bone. (a damp plastic glove filled with red gelatin or ice)
Now touch his ear. He nevermore will hear! (a dried apricot)
This is his nose. T'will never smell a rose. (a pickle, a hot dog or a soft chicken bone)
These worms are all that's left to feel. For them Brown was a lovely meal! (wet spaghetti)
After the lights back on and everyone has finished writing down their guesses, collect the papers. As you check their guesses, you can show everyone what was really in the cups. Give a nice prize to the person with the most correct answers.