A misspelling of 'monkey', that came from the word spnak.
Back on Usenet, if you wanted to kill a stupid thread, you'd quote the relevant part and then say
SPNAK style mispellings have been a trait of Junyer who probably passed it on to everyone else ;)
We use 'mnokey' interchangibly with 'stupid person'.
Needless to say if you spnak the mnokey too much, you'll go bilnd.