"Dave" wrote -
>
> I'd read - but no way of knowing if this is accurate or not -
> that the word is an onomatopoeia, like a cork 'plonking'
> out of a bottle. I suppose it could also be the sound of the
> wine blooping out of a bottle as you pour it down a drain.
>

Quite accurate: As an old antipodean joke goes "To make (cheap) wine, you
just throw grapes into the air, and they come down "plonk!"

However, the expression is from Australian rhyming slang (a carry over from
convicts Cockney rhyming slang) "plonk" short for earlier "plink-plonk", a
corruption of French "vin blanc" which became "ving blong: (adopted by
Australian & New Zealand troops who fought in France in the 1914-18 Great
War).

It was in common usage in both countries from the 1930s - "Waltzing
Matilda" A fortified red wine of the kind that inebriates with speed and
economy is 'pinky' or 'plonk'.

In NZ 1949 "Rows of gaudily-labelled bottles of local 'plonk' stacked on
shelves behind the bar."

And for those who may have read Neville Shute's book "A town called Alice"
(1950) - "He asked me if I would drink tea or beer or plonk. 'Plonk?' I
asked. 'Red wine,' he said."

Actually, this link tells it all
http://www.worldwidewords.org/qa/qa-plo1.htm

--

st.helier