Characteristics
Lunfardo words are inserted in the normal flow of Rioplatense Spanish sentences. Thus, an average Spanish-speaking person reading tango lyrics will need, at most, the translation of a discrete set of words, and not a grammar guide.
Tango lyrics use lunfardo sparsely, but some songs (such as El Ciruja, or most lyrics by Celedonio Flores) employ lunfardo heavily. "Milonga Lunfarda" by Edmundo Rivero is an instructive and entertaining primer on lunfardo usage.
A characteristic of lunfardo is its use of word play, notably vesre (from " revés", reversing the syllables, similar to English spoonerisms). Thus, tango becomes gotán and café con leche (coffee with milk) becomes feca con chele.
Lunfardo employs metaphors such as bobo ("dumb") for the heart, who "works all day long without being paid", or bufoso ("snorter") for pistol.
Finally, there are words that are derived from others in Spanish, such as the verb abarajar, which means to stop a situation or a person (e.g. to stop your opponent's blows with the blade of your knife) and is related to the verb "barajar", which means to cut or shuffle a deck of cards.
Read more about this topic: Lunfardo