An American gets on a plane and finds himself seated next to a Pakistani. He immediately turns to the Pakistani and makes his move.
“You know,” says the American to the Pakistani, “I’ve heard that flights will go quicker if you strike up a conversation with your fellow passenger. So let’s talk.”
The Pakistani, who had just opened his book, closes it slowly and says to the American guy, “What would you like to discuss?”
“Oh, I don’t know,” says the guy, smiling. “How about nuclear power?”
“OK,” says the Pakistani. “That could be an interesting topic. But let me ask you a question first. A horse, a cow, and a deer all eat the same stuff – grass. Yet the deer excretes little pellets, the cow turns out a flat patty, and the horse produces muffins of dried poop. Why do you suppose that is?”
The American guy is dumbfounded. Finally he replies, “I haven’t the slightest idea.”
“So tell me,” says the Pakistani, “How is it that you feel qualified to discuss nuclear power when you don’t know sh-it?” 
