Was it racist? Of course it was, she is a white woman making a joke about a person of a different skin.
Was it deliberately meant to harm anyone? Of course not!
I have worked in places where there have been many people of different ethnic backgrounds and yet no matter what we called each other, (and compared to Sarah Kennedy, (who I can't stand)),
Our remarks to each other should have caused WWIII, but we knew there were boundaries, said with a smile and being ready to be called 'white sh*t', and laugh was as harmful to me as working in a dark tunnel was to the darker coloured workers, we
ALL had to smile to be seen!