A lady goes into a veterinarian's office holding a limp duck under her arm. She says to the vet "we've had this duck for many years. I think he's dead, but we love him and want to make sure."
The veterinarian takes the duck, puts it on his examining table, examines the duck and says "I do believe he's dead, but do you want a further test?" The woman nods her head.
The vet whistles and a large black Labrador retriever comes out, puts his paws on the edge of the table, sniffs the duck thoroughly up and down, turns to the vet, and sadly shakes his head. The vet says "I guess your duck is really dead." The woman says "Are you absolutely sure--is there another test?" The vet whistles again and this time a large cat appears, jumps on the table, sniffs the duck, and shakes her head.
The vet says "the duck, I'm afraid, is dead." The woman accepts this, and asks about the bill. The vet says the bill is $500. The woman says "$500 is a lot of money just to find out my duck died." The vet says "Well, my own exam is only $100, but it was $200 for the Lab test and $200 for the Cat scan."