(via Wikipedia) Lunfardo (from the Italian lumbardo or inhabitant of Lombardy in the local dialect) is a dialect originated and developed in the late 19th and early 20th centuries in the lower classes in Buenos Aires and Montevideo, the surrounding area Greater Buenos Aires,[1][2] and from there spread to other cities nearby, such as Rosario, places with similar socio-cultural situations.
Originally, Lunfardo was a slang used by criminals and soon by other people of the lower and lower-middle classes. Later, many of its words and phrases were introduced in the vernacular and disseminated the Spanish of Argentina, and Uruguay. Nevertheless, since the early 20th century, Lunfardo has spread among all social strata and classes by habitual use or because it was common in the lyrics of tango.