The so-called negros curros, free African-descended Cubans traditionally considered to be of Andalusian origin, lived in the slum neighborhoods of Havana at the end of the 18th century and the beginning of the 19th. They were a marginal group known for their criminal activities, their dress, their attitudes, and their speech. These characteristics made them attractive to some Cuban authors, who included them as characters in their works. The present article intends to describe their characteristic language: an argot similar to the one used by members of the Peninsular underworld in earlier centuries. Along with this jargon were traits specific to Cuban Spanish and vulgarisms, result of their lack of formal education.