There should really be a word for the particular audience-produced sound that isn’t technically a boo—what audience actually, literally “boo”s anymore?—but that conveys the idea of boo-ness. That low, buzzing hum of disapproval—the collective gasp, the collective did they really just say that, the collective horror emoji, manifested as sound—that expresses, wordlessly, “too far” and “too soon” and all the now-classic responses to tasteless comments.