The Hunter Theory :

A 90 years old Man goes to a Doctor, “My wife is 19 years old and she is pregnant, what would be your opinion?”

The Doc replies, “Let me tell you a story. A hunter in a hurry took an umbrella instead of his gun. He sees the lion and points the umbrella at the beast... “Bang!” “Bang!” and the lion drops dead.

To which the man says, “That’s impossible, someone else must have shot the lion.”

Doctor, “Exactly! Now you understand.”