Never Mess with Kids :

 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 d kid): How about nuclear power?

 Kid: Very interesting topic. But let me ask u a question... Horse, cow & deer, all eat grass. Yet deer excretes pellets, cow flat potty & horse clumps.Why?

 Man: I don't know.

 Child: Do you really feel qualified enough to discuss nuclear issues when you don't know shit.