'Feen' is a new word for me and apparently means to crave something or someone. I gather it comes from people mis-hearing 'fiend'...but when and how did fiend become a verb and taken on that meaning?

Used by people who listen to other people who have no idea what they are talking about. At some point I assume somewhere between Generation X and Y someone overheard a word being used and misinterpreted it. Now legions of people born after 1977 are saying the word Feen. The word used which they misheard is Fiend defined as a person who is craving something in a maniacle way.

http://www.urbandictionary.com/define.php?term=Feen

Thanks zbeckabee. You never know with the urban dictionary if it's a spelling mistake or some new word that's just been invented.... I like the way they've made maniacle(sic) just a bit more like manacle than the original.

I heard feen on that Macy Gray song:

'I play it off, but I'm dreaming of you
I'll keep my cool, but I'm feening

I try to say goodbye and I choke
Try to walk away and I stumble'

Another version of the lyrics had fiending rather than feening.