If a black fan cheers for the only black hockey player on the ice for no reason other than because he is black, is that racist?

If a Rotti place refuses to make their rottis as spicy for white people as they do for black people, is that racist?

It's not racist to call an Australian an 'Aussie', or a british person a 'Brit' , but it is racist to call an aboriginal an 'abo'....why?