You dont know shit

Little Johnny is on a plane and next to him is a stranger. After a while the starnger turns around ans says to Little Johnny
"do you know that flight journeys seem to be shorter if you have a conversation with the person next to you ?".
Little Johnny who was busy reading a book reluctantly puts it down.
Little Johnny : "No"
man: "OK. So why dont we start one ?"
Little Johnny : "OK. Whats the topic ?"
man: "i dont know. how about nuclear energy ?"
Little Johnny : "before we start that, i would like you to answer one of my questions"
man: "sure. go ahead"
Little Johnny : "why is it that cow droppings are big and flat and out of shape whereas that of a goat is small and spherical ?"
man: "i have absolutely no idea"
Little Johnny : "then how is it that you feel qualified to talk about nuclear energy when you dont know shit ?"