In Reply to: Kiwi Gran and the other Plonkers posted by wally on Wednesday, 21. October 2009 at 11:11 Bali Time:
According to Wikipedia, "Plonker is a slang term of British or Australian origin whose meaning has evolved over time. Partridge in the third edition of his A Dictionary of Slang and Unconventional English in 1949 recorded the term as "low" slang for penis, "since ca. 1917". The term remains in recent use with that meaning."