An analysis of a valenced corpus of English words revealed that words that rhyme with slurs are rated more poorly than their synonyms. What at first might seem like a bizarre coincidence turns out to be a robust feature of slurs, one arising from their phonetic structure. We report novel data on phonaesthetic preferences, showing that a particular class of phonemes are both particularly disliked, and overrepresented in slurs. We argue that phonaesthetic associations have been an overlooked source of some of the more peculiar, arational aspects of slurs. We conclude by drawing broader morals about the evolution of the lexicon.