"I've never been better," he replies. "I've got an eighteen year old bride who's pregnant with my child! What do you think about that?" 

The doctor considers this for a moment, then says, "Well, let me tell you a story. I know a guy who's an avid hunter. He never misses a season. But, one day he's in a bit of a hurry and he accidentally grabs his umbrella instead of his gun. So he's walking in the woods near a creek and suddenly he spots a beaver in some brush in front of him. He raises up his umbrella, points it at the beaver and squeezes the handle. BAM! The beaver drops dead in front of him." 

"That's impossible!" said the old man in disbelief, "Someone else must have shot that beaver." 

"Exactly!"