Check out this article: http://www.bbc.co.uk/blogs/worldhaveyoursay/2010/06/_in_bristol_a_black.html

Urban dictionary - not in general to be trusted as a source of anything. Urban Dictionary: coconut https://www.urbandictionary.com/define.php?term=coconut A coconut is a person who like the fruit, is white on the inside yet brown on the outside. Eg. Indian This person may like to party, drink alcohol,have boyfriends, ... Urban Dictionary: Coconut Water https://www.urbandictionary.com/define.php?term=Coconut%20Water Hip people are drinking coconut water as a natural energy drink. Sadly, claims of great health benefits are unfounded! Urban Dictionary: coconut girl https://www.urbandictionary.com/define.php?term=coconut%20girl Jun 20, 2016 - A girl who can be hard and tough towards you ( like the out side of a coconut) but at other times can be sweet and filled with freshness ( like the ..

Less common, perhaps: It was once used in some parts to indicate someone who came form an area with lots of coconuts, eg Pacific Islands, though not while they were present, unless they were a good friend.

It is a term used to describe someone as being "white inside" - so despite the character looking Hispanic, she is white inside (white in mentality / culture etc)