fiending n. craving, desiring, wanting, obsessing (over or about). Editorial Note: This term originally referred to drug addicts but is now trivialized and generified. It acts primarily as a verbal noun. Feenin is a very common alternate spelling popularized by the song of the same name by the hip-hop artist Jodeci on the 1993 album Diary of a Mad Band. (source: Double-Tongued Dictionary)
Looks like it’s a replacement for “jonesing,” eh?