Why and the 3rd person

So recently my 3 year old and 5 year old always ask "Why?" to everything, and it is driving me nuts. For example picture this: A nice summer day and we are driving along, when we see a woman and two dogs, my 5 year old asks me "Daddy, did I see two dogs?" I answer yes and she asks "Why?". My reaction is not one of anger but one of frustration. I kind of ask her if she just asked me why, and she responds "Why?" again. I try to ignore this, but have the thought running through my head that had something to do with the ocular nerve and brain neurons, all things that I know she won't get right now, but in about 6 months she will be teaching me.

So we get home and she goes up to my wife and says "Mira saw a woman and 2 dogs." All of a sudden she is now not only asking why but referring to herself in the 3rd person. We try to go with the flow, and then tell her we won't answer her if she is speaking this way. Well the kid is way smarter than that. She knows mommy and daddy are not going to ignore her so she smiles and keeps doing it.

This lasted about 1 month and we might have her over it. However, anytime she asks us a question we flinch as we answer it because we know the inevitable question to our answer is "why?". And my answer to that is "I have no idea." Not a far stretch of the truth.