It all comes down to the context in which any term is used - where as in this case that username is not even remotely racist. PC do gooders need to have their head read with some of their ridiculous overeactions.
The problem with context is that you can't easily define it when it is in the form of the written word.
In this case the very fact it has ignited this conversation would suggest that some here find it at best childish and at worst offensive.
The poster can call himself whatever he likes, but if people are uncomfortable with that name are they not allowed to say?
Also this notion that anyone who dares to question anything that is said online is an over-reacting pc do - gooder is in itself an over-reaction.
