Many thanks, everybody. I gather from your information that it is some form of dialectal expression (perhaps just Canadian?), and tsuwm provides an example in the singular, which is interesting.

Jackie, who on earth is Whiskers-on-the-Moon? [goggly-eyicon]

Inselpeter, the speaker is referring generally to Corcoran's way of not beating around the bush and speaking plainly even when he's negotiating something shady. In this case, they've been unmistakeably overheard while Corcoran was offering the speaker money in exchange for his vote, and the speaker accepted it.