A little "tail"

So we were driving home the other day when N saw a dog on the side of the road.  The conversation went something like this: 

N:  "I see a doggie!"  

Me: "You do see a dog!"  Very exciting conversation.  

N: "doggies have tails!"

Me: "You're right N, doggies do have tails."

N: "Kitties have tails too!"

Me: "Good job, N, kitties have tails too."  Then, lest you forget who's kid he is...

N: "Airplanes have tails, and helicopters have tails!"  

Yes, only in our family could we make the jump from doggies and kitties to airplanes and helicopters...