Gong farmer was a term that entered use in Medieval and Tudor England to describe someone who dug out and removed human excrement from privies and cesspits; the word "gong" was used for both a privy and its contents. Gong farmers were only allowed to work at night, hence they were sometimes known as nightmen. The waste they collected, known as night soil, had to be taken outside the city or town boundary or to official dumps for disposal, from where it might be taken to be spread as fertiliser on fields or market gardens. 

They were only allowed to work between 9 pm and 5 am, were permitted to live only in certain areas, and because of the noxious fumes produced by human excrement were sometimes overcome by asphyxiation. Gong farmers usually employed a couple of young boys to lift the full buckets of ordure out of the pit and to work in confined spaces.