Man takes his pet duck to the vets only to be told by the vet that his pet duck is dead.
"I want a second opinion" says the man, so the vet ushers in a Labrador dog who sniffs the duck and then shakes its head, and the vet says "there you go, the duck is dead" But the man wants another opinion so the vet fetches his Siamese cat who, like the dog, sniffs the duck and shakes his head - after which the man concedes that the duck is dead and asks for the bill.
The vet hands him a bill for £1,200 and man main exclaims that this is a ridiculous amount. The vet replies "It would have been £50 if you accepted my initial opinion that the duck was dead, but since then you've had a Lab-test and a CAT-scan".