from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Background noise of several "conversations," none of which is decipherable since all the actors are actually just repeating the word rhubarb (chosen because it contains no very sharp or recognisable phonemes), or other words with similar attributes.
- n. Speech which is undecipherable to the listener because it is in a language he or she does not understand; mumbo jumbo.
- n. Blah blah; etc, etc.
From rhubarb, sense 3 (Wiktionary)