The tag ‘Jacko’ which is just half of the full nickname which goes like, ‘Wacko Jacko’ by the media was not justified. According to many people, this nickname seems to have racist origins. Moreover, since Michael Jackson was a person who was loved by many, King of Pop was a more appropriate tag which could be used everywhere.
As far as the racial origins of Wacko Jacko go, there is not enough evidence of when and why this nickname truly emerged. All that people do believe is that this nickname did not do justice to the overall popularity and the respect that MJ had gained.