A policeman pulled me over last night and asked, “Have you been drinking tonight, sir?”
“Yes” I slurred, “But I’m not over the limit.”
“We will let the breathalyser decide that” he replied. “Take a deep breath and blow into this until I say stop.”
Within a second the policeman shouted, “Stop!”
“Blimey, that was quick” I said, “What did I blow?”
He said, “My finger.”