Yeah, yeah, I know. Sounds like a made-up word or something. Well... it is.
It's origins are almost lost in the mists of time, or at least in the mists of my internet time. When I was in college in the early 1990s, I was a bit of an IRC and USENET addict, as well as a big fan of Mystery Science Theater 3000. You may recall the old story that in movies, when they wanted a background crowd of extras to sound like they were in conversations, they would repeat the word "rhubarb" over and over again.
Anyways... the guys on MST3K used to make jokes along those lines and for some reason I used to find it really, really funny (I'm very easily amused). So, when I was looking for a nick to use on IRC, etc. I decided that "rhubarb" would be funny to use, since it was associated with random babbling (which was, and still is, quite appropriate for much of the stuff on the internet). But, alas, it was already taken. So, then I had the bright idea of sticking my initials on the end - L.E. At first, I think I intended it to be read Rhubarb L. E., but I quickly realized that it was a pronouncable "word" as rhubarble. And thus, the word/name was born.
If you hadn't already guessed, the word still has a 'random babbling' assocation for me!
On a whim, I decided to see what the Oxford English Dictionary had to say about the use of "rhubarb" in the movies and found the following entries. There is also the adjective "rhubarby", but no rhubarble!
<snip stuff about vegetables>
4. a. The word ‘rhubarb’ as repeated by actors to give the impression of murmurous hubbub or conversation. Hence allusively.
1934 A. P. HERBERT Holy Deadlock 194 The chorus excitedly rushed about and muttered ‘Rhubarb!’ 1952 Radio Times 17 Oct. 11/3 The unemployed actors had a wonderful time. We'd huddle together in a corner and repeat ‘Rhubarb, rhubarb, rhubarb’ or ‘My fiddle, my fiddle, my fiddle’and it sounded like a big scene from some mammoth production. 1958 Observer 7 Dec. 18/5 Actors, who shout ‘rhubarbrhubarbrhubarb’ to give the impression of a distant riot. 1960 J. BETJEMAN Summoned by Bells ix. 105 And in the next-door room is heard the tramp And ‘rhubarb, rhubarb’ as the crowd rehearse A one-act play in verse. 1972 P. DICKINSON Lizard in Cup xi. 174 The conversation..was meaningless; they might just as well have been muttering ‘rhubarb, rhubarb’. 1976 Gramophone June 71/2, I wondered if the chorus would have made a better effect had the words been less clearly articulated (like actors in a crowd scene muttering ‘rhubarb’)
d. slang. Nonsense, worthless stuff.
1963 Radio Times 3 Oct. 17/1 Dig this Rhubarb..a new kind of television entertainment... Which (we hope) will prove that there is no shortage of writers for television so long as you are not particular about whether they are still alive or not. 1976 Telegraph (Brisbane) 6 July 12/2 They gave me some rhubarb about violating the firework zone. 1977 Times Lit. Suppl. 3 June 673/1 Peking opera..employed..a huge repertoire consisting almost entirely of rhubarb. 1979 Times 22 Feb. 5/7 We should look at the individual... Whether he or she went to the right school..that's rhubarb.
intr. Of an actor: to repeat ‘rhubarb’ (RHUBARB n. 4a); to mumble indistinctly in order to represent the noise of a crowd. Freq. transf. in gen. use. Also redupl. Occas. trans. with direct speech as obj.
1958 Spectator 11 July 47/1 ‘Hear, hear,’ they rhubarb-rhubarbed. 1965 Observer 20 June 25/5 The barons, mildly rhubarbing in some awkwardly symmetrical pieces of stage grouping, rightly suspect the King of double-dealing. 1966 I. JEFFERIES House-Surgeon iv. 79 We rhubarbed till he had gone. 1967 D. SKIRROW I was following this Girl xxxv. 210, I listened hard and rhubarbed my way through, trying to make any sort of sense of what I was hearing. 1976 Daily Tel. 21 Sept. 11/2 Livia faced the Roman mob, all seven of them, rhubarbing at the Palace back door. ‘You wait,’ she cried imperiously, ‘until my husband gets home!’
So rhubarber, an actor who repeats ‘rhubarb’; also transf.; rhubarbing vbl. n. and ppl. a.
1953 A. MCQUEEN Let. 31 Aug. in Partridge Dict. Slang Suppl. (1961) 1247/2 When a few actors gathered backstage and represented ‘noise without’ made by a mob, they intoned the sonorous word ‘rhubarb’. The action was called ‘rhubarbing’, the actors ‘rhubarbers’. 1965 New Statesman 20 Aug. 266/2 A floodlit market place at night with hucksters arriving to tempt the rhubarbers. 1970 Times 27 Feb. 13/5 The few attempts at pageantry generally come to grief against painted backdrops, watched by a handful of rhubarbing commoners. 1978 Daily Tel. 10 May 36/6 Mr Jenkin showed himself to be a formidable rhubarber in his own right. He nodded and moved his lips with the utmost vigour.