Stabbed

A quiet little man was brought before a judge. The judge looked down at the
man and then at the charges and then down at the little man in amazement. "Can
you tell me in your own words what happened?" he asked the man.
"I'm a mathematical logician dealing in the nature of proof."
"Yes, go on," said the astounded judge.
"Well, I was at the library and I found the books I wanted and went to take
them out. They told me my library card had expired and I had to get a new one.
So I went to the registration office and got in another line. And filled out my
forms for another card. And got back in line for my card."
"And?" said the judge.
"And he asked 'Can you prove you are from New York City?' ...So I stabbed
him."