plonk [L19th] There are two different plonks. One, as in ‘to plonk something down’, was originally a northern English word meaning ‘to hit or strike with a heavy thud’, and probably comes from the sound. The other plonk [1920s], describing cheap wine, started out in Australia. It is probably humorous form of blanc in the French phrase vin blanc ‘white wine’. Plonker, meaning ‘an idiot’, dates from the 1960s but was popularized by the 1980s BBC television sitcom Only Fools and Horses. It is based on the first plonk and was first used to mean ‘something large or substantial’ and also ‘penis’.