I tried to find out. I asked around. One of my friends employed the term frequently, and I assumed she knew what it meant; when I asked, she said, "I think it's a contraction of 'fuck with,' as in, 'I won't get involved with someone who fucks with me emotionally,' therefore, an 'emotional fuckwit.'"
Which seemed both reasonable and wrong. I knew I had to keep looking. And now I have an answer to my question, thanks to a useful, thorough and quite specific lexicon: The F Word, edited by Jesse Sheidlower, which I got from my university library.
Turns out fuckwit is a stronger form of, say, halfwit or nitwit. There it is, defined on page 197, after fucked up and fuckwad, and before fuck with, fucky and fuck you:
FUCKWIT, noun, Chiefly Australian and British a stupid person, Hence fuckwitted, adjective stupid; fuckwittage, noun, stupidity.Examples of usage include
1968 A. Buzo, in Plays 89: Well, ta-ta for now, fuckwit. 1970 S. Jarratt Permissive Australia 142: Of course they do, you fuckwit. 1971 in J. Hibberd Stretch of the Imagination 40: You two-timing, fuck-witted mongrel of a slut!Now there is an epithet worth remembering. And aren't we all edified by and grateful for this lesson?