There was this man that had a dog. He came home one day, and his dog was belly up with its legs sticking in the air.
He wasn't sure if it was dead or not, so he took it to the vet. He told the vet of his problem, and the vet said that there was a sure-fire way to see if the dog is indeed dead.
He left the room and returned with a cat. He rubbed the cat in the dogs face, and after a while came to the conclusion that the dog was indeed dead.
The man was upset and asked the doctor how much he owed him. The doctor said, "$550" The man was stunned. He asked the doctor to explain and the doctor said, "Fifty for the visit, and 500 for the cat-scan..."