A sort of gibberish or patter that seems plausible but is nonsense, done for amusement: Danny Kaye excelled at double talk
Deceptive and insincere speech: Don't be put off by his double talk(1938+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with double talk
Meaningless speech, gibberish mixing real and invented words. For example, Some popular songs are actually based on double talk.
Also,doublespeak. Deliberately ambiguous and evasive language. For example, I got tired of her double talk and demanded to know the true story, or His press secretary was very adept at doublespeak. This usage dates from the late 1940s, and the variant from about 1950.