Gwoon originated in the NES video game
Dragon Warrior IV. Random monsters and dragons in towns throughout the game would reply "Gwoon, Gwoon." when spoken by the heroes.
These days the term is used on a few people on IRC who would classify themselves as an asshat. Much like in the game, the word itself is utterly devoid of meaning, and used to fill in
conversation lulls, or as an noun/adjective when words fail the user.
The word can also be used as a greeting in the presence of other gwoon-using asshat friends.
Multiple o's may be added for emphasis, as much as emphasizing a nonsense word is possible.
"Gwoon, Gwoon." "Gwooooooooooon."