It was a convention of obscenely comic verse that oral sex caused bad breath that was nearly toxic. "Whores of the alleyways" are contaminated from giving oral sex; Catullus refers to "the foul saliva of a pissed-over whore". The urinary function of the penis makes oral sex particularly repulsive to Catullus, who elsewhere reviles a Celtiberian for brushing his teeth in urine. Martial jokes that a fine perfume turned to "garum", fish sauce, when it was sniffed by a man whose breath was putrid from oral sex. In another of Martial's epigrams, a "fellator" breathes on a hot cake to cool it down and turns it to excrement. The bad breath and rotten teeth that are attributed to performing oral sex represent moral decay and a general corruption of the mouth's positive functions as the organ of a citizen's persuasive speech.