Three doctor are in the duck blind and bird flies overhead.
The general practitioner looks at it and says,
"Looks like a duck,flies like a duck,it's probably a duck,"
shoots at it but misses and the bird flies aay.
The next bird flies overhead,
and the pathologist looks at it,then looks through the pages of a bird manual,and says,
"Hmmmm,green wings,yellow bill,quacking sound,might be a duck."
He arises his gun to shoot it,but the bird is long gone.
A third bird flies over .
The surgeon raises his gun and shoots almost without looking,brings the bird down,and turns to the patholoogist and says,
"Go see if that was a duck."