The official language of Argentina is Spanish.
This is a direct consequence of the fact that the language was spread during the conquest. Afterward however, due to native influences that were added to those brought by the immigrates in the XIX and XX centuries, of very distinct origin, the Spanish language spoken in Argentina adapted itself to one engendering new vocabulary. The language was thus individualized.
Particularly in Buenos Aires, this Spanish “agiornado” (a mix of argentine Spanish, vernacular dialects and distinct unclassifiable expressions) acquired a singularity. Furthermore, a distinct voice was formed in the beginning of the XX century: “lunfardo,” which is slang that has penetrated even into the upper classes and that especially the tango community adopted and promoted as an alternative and local language.
The importance of this development is seen in the creation of the Porteña academy of lunfardo in 1962, which catalogues this slang.
A few examples of such words include: che, gil atorrante macanudo morfar, pilcha, pibe, etc., which mean “you,” “idiot,” “bum,” “cool, agreeable,” “eat,” clothes,” and “kid” respectively.
Source: 365 Info Buenos Aires