An engineer was seated beside a little girl on an intercontinental flight. He said: "Let's chat a while; it seems that trips pass faster if you talk with someone."
"Fine," said the little girl. "What do you want to talk about?"
"How about nuclear physics?" he answered.
The little girl said, "Look here: a deer, a cow, and a horse all eat the same thing--grass. However, the deer craps out little pellets; the cow makes flat pies, and the horse makes great green turds. How do you explain that?"
The engineer thinks and then says, "Gosh, I just don't know!"
Then the little girl says, "How do you expect to talk about nuclear physics when you don't even know shit?!"