A sort of rhetorical grab bag has accrued over the years: an assortment of tropes, turns of phrase, misrepresentations, allusions, and implications that are recycled and uttered like a ritual whenever the topic of various antirealist positions comes up; typically moral relativism, but on occasion you’ll see references to nihilism or antirealism (though you’ll be unlikely to see direct references to error theory or noncognitivism unless you’re dealing with someone with an academic background or who is pitching their objections in a moral academic context).
I’ve noticed the same thing, even among moral realists. Some theists will use the “really” weasel word against nontheistic moral realists.