A word commonly used to describe those who are lowlife and have no realistic goals with their lives. Often used to also describe those who are criminally inclined, enjoy bullying others for pleasure and entertainment, think that they are champagne in a fall glass when they're luke warm piss in a cup and act like they are the village hardman but are nothing more than a cowardly quim on the side of the road.
A person that attempts to have sex with as many women as possible, while, at the same time, trying to keep it a secret from each woman. In his head O.S thinks that the illusion will last, however, that is not the case. Often most of these women know each other. If your friend is an O.S, best thing to do is let it take its course. Then when the shit hits the fan, kick back, pop open a cold one and enjoy the show.
Bob-"Hey whats up O.S?"
British Simon -" O.S? Operating system?"
Bob-" Nah. Operation scumbag."
An individual who does not quite possess the capabilities of a contemptible full blown scumbag and is therefore referred to as a Piece of Scumbag (POSB). It is often feared that POSB's will realise their full potential and evolve into their more powerful form.