Many of these expressions from Urban culture, both Black and White, are found here: http://www.urbandictionary.com
Urban dictionary

In this dictionary, see 'hoe.' Several quotations give a good idea of the use of the word.
Not a documented site, with many invented by the person submitting the usage, but useful to one like me who is far from urban American life.

Nappy is on page 21 of the 'N's, giving an idea of the extent of this website. Both UK and American uses of the term, but look at all the other slang using nap-