A lady went running to a doctor with a badly spoiled stomach.  
"What did you eat for dinner last night?" asked the doctor.
"Oysters," she said.
"Fresh oysters?" asked the doctor.
"How should I know?" said the lady
"Well," asked the doctor, "couldn't you tell when you took off the 
shells?"
"My Gosh," gasped the lady.  "Are you supposed to take off the shells?"