Gibberish (also gromolo) is a kind of pretend language which consists of a series of imaginative, but meaningless letter and word sequences.
Gibberish finds usage in forms of improvisational theater in which individual sentences of entire dialogues can be held in gibberish. However, the audience and the actors are supposed to be able to reconstruct the plot as much as possible with it among themselves through the mimicry and gesturing of those speaking gibberish. Thereby, the use of gibberish is also conducive, besides for the dialogue, for the training of the body language of the actors.
Gibberish is also employed in the area of electronic warfare to interfere with voice radio networks. Tapes with gobbledygook resembling the language of the corresponding target networks (or general gobbledygook) are broadcast by jammers to deceive enemy detection or to interfere with radio networks.
Foreign language gibberish
One particular form of gibberish is when these senseless words sound like a particular foreign language. Of course, it requires knowledge of typical sounds of that language, for example, the guttural "ch" in the Arabic or the German language.
A good example of Bernese German gibberish is "Das Totemügerli" by Franz Hohler. In it he tells a story with a lot of completely freely invented words, which, however, impart a meaning (although many of the words do not exist at all).