My mum dealt with this a lot, but her most common story was about my little sister. When she was about 3 she saw an indigenous woman pushing a pram through the shopping centre. My little sister loved little babies and was curious. Dragging mum over she stopped at the pram and asked "May I please see your chocolate baby".

Mum said the woman was very good humoured and was more impressed with my little sisters manners than the colour inference.

Children are extremely innocent and do not actually see that what they have said is a negative thing. Most people are aware of this and are good natured when a child blurts out an uncomfortable observation. It is very hard for them to understand, but we can only explain to them that words can make people feel sad and you need to be more careful with what you say.