River Plate Spanish
Castellano Riverplatense or River Plate Spanish (also Rioplatense Spanish) is the Spanish that is spoken in the Buenos Aires area as well as the area of Uruguay across the Rio de la Plata. River Plate is also the name of a top soccer team here in the city.
This kind of Spanish is laced with Lunfardo. Lunfardo is a dialect spoken by mainly the lower classes in the city.
Wikipedia has excellent articles about River Plate Spanish and Lufardo. No need to c&p in here. Just visit the links.
If you want to hear it? I guess you will have to come for a visit!