Germanía or jerigonza is the term used in Spanish to refer to the argot used by criminals or in jails. Its purpose is to keep outsiders out of the conversation.
We already have some documentation in picaresque works from the Spanish Golden Century. Some writers used it in poetry for comical effect.
Since the arrival of gipsies and their frequent imprisonment, it incorporated lots of vocabulary from Romany language and its descendant, the Gipsy jargon caló. As time passed, several words entered popular use and even standard Spanish, losing their occultation value. It survives today in the cheli jargon.
War of the Germanías
The term germanía ("brotherhood" in Catalan, compare with Galician irmandiño) originated from the name of certain communities in the Valencian Country, Spain, which made themselves notorious by having rebelled against the local nobility during the sixteenth century. Subsequently, the term referred to the argot used by these communities and, eventually, it referred to improper argot.
They might not make it to the inbox of grammar mavens, but I use similar cases in my intro linguistics course, to help make the point that children's language games are based on their implicit understanding of phonology, not on spelling.
Spanish-speaking children -- who often learn the jerigonza game before they learn to read -- would think in terms of the categories of their natural and internal phonology, rather than in terms of letters of the alphabet.
In the same form of quasi-phonetic writing, the jerigonza version would be /e-pe skwe-pe la-pa/, with six syllables, not /e-pe sku-pu e-pe la-pa/, with eight.
This wordplay receives different names in different Spanish-speaking countries: jeringozo in Argentina and Uruguay, jeringonzo in Colombia, jerigonzo, jerigonza or jerigoncio in Chile, and so on.
Most names derive from the Spanish word jerigonza, which can mean either jargon or gibberish.
This game, with almost identical rules but using the Brazilian Portuguese language, is popular with Brazilian children under the name of LÃngua do Pê (Portuguese for P-language).