An adjective to describe a person or situation that is "iffy" or awkward and unsure. Can be used when you're just in a funk and not sure what adjective to use.
Derogatory word for an immature fan of science fiction, or sci-fi. A science fiction fan who doesn't have a realistic attitude toward the genre, but thinks that science fiction is the be-all ad end-all of his/her life.
Look at that skiffy over there with the Spockears. Let's hit him with the Shrek slime!
Onomatopoeia for the word sci-fi as a derogatory label towards the softer forms of science fiction (i.e. space opera, science fantasy, Doctor Who, the Marvel/DC Comics universes, etc.). Most users of the word are purists that reject anything not grounded in some semblance of reality (or, failing that, fringe science).
The Sci-Fi Channel became total skiffy the moment they renamed to SyFy.