from: the on-line hacker Jargon File, version 4.2.3:

plonk excl.,vt. 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.

lil mad is like big mad but the opposite, you mad but not mad to the extent of pullin somthin

The sound a user makes as it hits the bottom of another user's killfile bin

in Australian slang -

1: wine. usually referring to cheap wine but not neccessarily.

2: to place something down on a surface (even one's bum).

A word used on message boards as a response to some turd, to let them know you've just put them on ignore.

rhyming slang for cheap white wine.

bottle of blanc (white) = plonk