Throughout the history of science, novel ideas that diverge from mainstream thought have often been met with condemnation, derision, and ad hominem attacks. These reactions have sometimes led to the premature rejection of such ideas, only for them to be later revived and even accepted as the prevailing paradigm. While robust debate is essential in science, the use of derogatory language is unethical, for it discourages research on existing hypotheses, deters funders, corrupts the scientific record, and delays or prevents the advancement of science. In this article, I discuss the case of unethical language repeatedly used against proponents of the hypothesis that an extraterrestrial impact event triggered the Younger Dryas cool period.