I just met someone who was using the expression in the Northeast in the early 80s. He said that unless you were being jokingly provocative or an asshole no-one would ask for a monkey fuck–just as no-one would ask for a Dutch Kiss. You’d just ask normally, like “can I get a light off your cigarette,” and then smile and acknowledge “monkey fuck.”
However, I’d be extremely cautious if this guy asks you for a monkey fuck.
At any rate, you’ll be pleased to know I found the source of the expression: a self-monkey-fucker.