It's from Dilbert, or more specifically, one of the DNRC* newsletters. Scott Adams ran a contest for a name the DNRC memebrs could use for non-DNRC members. "Cow-orker" was one of the winning ones.
And I though it was some one practicing animal husbandry. :)
Alex "Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened." -- Winston Churchill (1874-1965)
At least. Actually I suspect "In-duh-vidual" was first and some months later someone else came up with "cow-orker" which Scott liked better. Or perhaps liked for a different context.