though there is not an exact definition for the word it is usually used as a reference to something of a sexual nature. it generally means someone erotic.
"hey hows micheal doing did you get with him"
"oh ya i did he's such a fucking cow spanker"
A dairy farmer or stockman. (New Zealand origin)
The man whom spends time with cows on their last night on the farm before being sent to a slaughterhouse. (American Origin)
"Forget going to this place called Walmart...I'll hit up the cow-spanker down the street for milk". (NZ)
Guy One: "Damn...that sucks for John."
Guy Two: "Why...because he has to stay late?"
Guy One: "No...he's the cow-spanker this week..."
Guy Two: "He is either going to love or hate that steak dinner tomorrow!" (American)