What does Bhootni Ke mean?

Bhoot means ghost and bhootni is a female ghost. But In india, ghosts are percieved as being black in colour. Therefore, when some one who was very dark in complexion and did something inappropriate, offensive or disturbing to his entourage, he was condemned by being called "bhootni kay". But now it is not only applied to dark skinned people, it has rather become a profane remark to any one who is being mischievous.