How to explain a stutter to a child?

How to explain a stutter to a child? I was doing a voice chat with my sister and 4 year old neice today and she asked me "Why do you go c-c-c?" I tried my best to explain and she seemed to accept it no problem, just wondering if anyone has any experience with this. Also I'm trying to have a kid of my own, any pointers that way would be greatly appreciated too.