These are one of the funniest kind of jokes because the Medical profession is otherwise a serious profession.
Three doctors went duck hunting and a bird flew overhead.

The general practitioner looked at it and said, "Looks like a duck, flies like a duck... it's probably a duck," and he took a shot at it but missed and the bird flew away.

When the next bird came into view, the pathologist looked at it, then through the pages of a bird manual, and said, "Hummmm... white wings, yellow bill, quacking sound... might be a duck," and by the time he raised this gun to shoot, the bird was long gone.

The surgeon raised his gun and shot down a third bird almost without looking, then turned to the pathologist and said, "Go see if that was a duck."