Rattle off words that you make up as you speak, taking care not to use any real words from any language that you know!
A common meaning of gobbledygook is speech or writing that is wordy and largely unintelligible. In that sense, gobbledygook is not a language but a style. For example, a young child, writing of a cow, might say that "a cow needs a head is so that the mouth can be somewhere." An adult writing gobbledygook might say that "the purpose of the cephalic structure is to provide an architecture that allows the oral cavity to be properly positioned environmentally." (The example is due to Sir Ernest Gowers.)
Examples of gobbledygook appear daily in political speeches and are often seen in academic writing. When the subject is psychology and the speech or writing is laced with trendy psychological terms, the style is often called "psychobabble."
Speech that sounds sensible but that has no meaning at all is often called "double-talk." Such speech has nonsense words mingled with real words. "I brought four gremlits of blamish in Plandome Road, but in Flangdin, where I got a few hahfrums of negrit, the reciprocity of the frammis gromulated."