From The Art and Popular Culture Encyclopedia
Gibberish is a generic term in English for talking that sounds like speech, but has no actual meaning (such as "ja sun tecumba tapar") or ("la bgud duyier jusrekd, oh mai!"). This meaning has also been extended to meaningless text or gobbledygook, such as "the cats are eating my shmibbleboop, someone save the prostate gland from defibble nozzle sands". The common theme in gibberish statements is a lack of literal sense, which can also be described as a presence of nonsense. In the realm of computers, the displaying or printing of binary (non-text) data due to a fault in hardware and/or software is called gibberish (e.g. simulated by entering "TYPE C:\WINDOWS\SYSTEM32\CMD.EXE" or "cat /bin/sh"). It is also a "language" frequently used by teenagers that can be understood, in which the words are divided by syllables and the first sound is spoken, followed by "idiga", then the last sound.
A family of language games in English are sometimes referred to as "Gibberish". Comedian Sid Caesar was noted for what he called "double-talk", an ability to speak varieties of nonsense syllables that sounded (to Americans) as if he was speaking various foreign languages.