In reference to players of MMORPG's that instead of taking a break to go to the bathroom, they take off their sock, defecate in it, and throw it aside for later disposal. Refers to someone who stays up all day and all night to play an MMORPG.
"Steve, how'd you make lvl 50 already? You were just lvl 45 a couple days ago. You friggin poopsocker!"