Plonk

This word is defined by the Oxford Companion to Wine as "[a v]ague and derogatory English term for wine of undistinguished quality ... a term of Australian slang that has been naturalized in Britain."

The Oxford Companion continues: "During the First World War the French vin blanc with its un–English nasal vowels was adapted in various fantastic ways, from 'von Blink', which sounded like a German officer, to 'plinketty plonk', which suggested the twanging of a banjo. This was shortened to 'plonk', which coincidentally was also British soldiers' slang for 'mud'. By the Second World War this had given rise to 'A/C Plonk' for aircraftman 2nd class, the lowest of the low in the RAF and hence parallel to plonk in the glass."

"Despite its etymology, plonk need not be white; and if the word suggests any kind of wine in particular it is cheap red served at a party. For this reason, colour–blind theories have sometimes been proposed, for example that it mimics the sound of a cork being withdrawn from a bottle. But it has no more to do with this sound than with the unceremonious plonking down of [a] glass."

I'm not sure whether all this supports the suggestion that the term originated in Australia, or not.