1) Happy black means to feel bittersweet about something.
2) Or similarly to feel happy about being depressed.
3) It can also be used to describe feeling happy about being different and not following the crowd etc.
This word, well phrase was invented by me in a poem I wrote a few months back. It makes no sense to anybody but those who feel it!
Enjoy using it in normal conversation when there's no other word you can think of to describe your confused teenage mood.
1) I'm feeling rather happy black today.
2) Man! How hyper were those people tonight, I'll be quite happy to go back to my sombre mood. (that's happy black)