One who masturbates to rosters; an enthusiast of fantasy sports or professional sports in general; one who watches ESPN SportsCenter twice a day.
Jim: Hey Mark what's up?
Mark: Not much bro I was just on my way home from work.
Jim: Hey, did you... *stops and checks his iPhone* What the fuck! Chris Bosh had only 10 fantasy points last night?!
Mark: Jim, quit it... I don't want to be associated with a rosterbator.