plonk definition, from Internet Connection, Inc.

[Usenet: possibly influenced by British slang ‘plonk’ for cheap booze, or ‘plonker’ for someone behaving stupidly (latter is lit. equivalent to Yiddish schmuck)] The sound a newbie makes as he falls to the bottom of a kill file. While it originated in the newsgroup talk.bizarre, this term (usually written “*plonk*”) is now (1994) widespread on Usenet as a form of public ridicule.