talking shit

A stranger was seated next to a little 5th grade girl on the airplane when the stranger turned to her and said, 'Wanna talk?'I've heard that flights go quicker if you strike up a conversation with your fellow passenger, the man said quietly.

The little girl, who had just opened her school book, closed it slowly and said to the stranger, 'What would you like to talk about?'Oh, I don't know, said the stranger. 'How about nuclear power?'OK, she said. 'That could be an interesting topic' But, let me ask you a question first, said the 5th grader.A horse, a cow, and a deer all eat grass, right?The man said 'Yes'The little girl said 'Yet a deer excretes little pellets, while a cow turns out a flat patty, and a horse produces clumps of dried grass. So, why do you suppose that is?'The stranger thinks about it a minute and says, 'Hmmm, I have no idea'.To which the little girl replies: 'Do you really feel qualified to discuss nuclear power when you don't know shit?'