Typically a young New Zealand bloke around the age of 14 - 25 who has had to much to drink and ends up "Rooting" a really ugly girl.
Tane: Bro!, did you hook up with Kim?
John: No way bro, you know i didn't !
Tane: "Whispers" Sickman.....
A term given to a person who regularly exhibits traits of awesomeness, or who generally acts in awesome ways, says awesome things etc.
Often stylised as "sikman" or "sicman", with extra "a"s for emphasis of the level of sickman-ness.
Chuck Norris is such a sickman.