“For an obscenity to work, it must be both inside and outside speech,” Ian Coutts explains in Quill & Quire (article not available online). Obscenities begin as ordinary words until, as children, we are told they are bad. “The power of obscenity comes from this paradox,” Coutts writes. “We must never say those words, but obviously we do–or they would be lost to all time.”
Obscenities are more than just paradoxical pleasures: They both separate us from and join us to the animal world, writes Coutts. Whereas an animal might yelp or cry in pain, humans have words to articulate these feelings. (Oh, s#$% that smarts!) But even as obscene language separates us from our animal kin, these naughty words also often refer to copulation and defecation, two of the fundamental functions we share with other living things.
Obscenities evolve with our culture, so as society becomes increasingly comfortable with bodily functions, Coutts predicts fresh swear words will emerge to reflect whatever is deemed newly unmentionable.