A man was seated next to a kid

A man was seated next to a kid in an airplane. The man turned to him and said, “Let’s talk”.
Kid: Ok, what do we talk about?
Man (making fun of the kid): How about nuclear power?
Kid: Very interesting topic. But let me ask you a question… Horse, cow & deer, all eat grass and yet deer excretes pellets, cow flat potty and horse clumps. Why?
Man: I don’t know.
Child: Do u really feel qualified enough to discuss nuclear issues when you don’t know shit???