Canadian people. Often used in the UK, possibly not used elsewhere, since Yank is mainly used by the British to refer to Americans. Cold Yanks being a joke about how hard it can be to tell the difference sometimes with American accents and Canadian ones, though Canada is much colder. It's not usually meant in a bad vibe way, more as a somewhat dismissive term of endearment.
"I thought from the accent they were surely Yanks, but they turned out to be Cold Yanks"
"What?"
"Cold Yanks. You know, Canadians".
Sex act, possibly in a dream sense., where one partner feeds the other a white claw; whilst holding said white claw with nothing more than their genitals.