"Turk" appears in the Oxford English Dictionary from at least 1699 as a synonym for "any cruel hard-hearted man" (as defined at that time).

It also appears in the chantey "Leave Her, Johnny":

"The mate was a bucko and the old man was a Turk."

As for "jerk," my NYC grandfather (born in the 1880s) used it all the time. Presumably it is from "jerk-off," but to people unfamiliar with that term (and there are lots of them), it would seem quite innocent.

My subjective feeling, however, is that McClintock meant "Turk," just as he sang it.