It's pretty obvious what 'choc-ice' means, when used by one black person of another. It means he's black outside, and white inside. Technically, it's 'racist', because it implies there's something wrong with being white. But what the hell? No-one is going to get murdered because of a bit of black banter. 

http://www.guardian.co.uk/football/2012/aug/17/rio-ferdinand-alex-ferguson-warned-twitter