A Scrub is a guy who thinks he's fly (also known as a buster) -- stick by "what they want", and usually sit on a broken tail bone.
Also a term to describe Shoto-players
Capcom misprinted movelist marquees in the mid 90s for their fighting games to read "mash (punch/kick) for extra damage" (see: Ken's Kick Super) . People would mash keys to gain more points out of supers; even for supers where this feature wouldn't work.
in SF2, people tried getting out of dizzy combos by mashing the buttons, which meant they were being dizzy combo'd to death constantly, and probably sucked.
This term reached popular misuse within online games (StarCraft/TFC/ Disney ToonTown), when nerds started filing for the internet in droves, because their fighting game skills sucked. Nerds on Bnet/Quake/Halo would become shut-ins and 'remake' fighting game terms to fit online games, where they naturally have nothing to do with them. The proper and only term they're looking for is "n00b".
1) "Are you a bogan, or a scrub?"
"I'm on the bus so I'm a bogan, but I've got to see doct about my butt, idk"
2)"omg I'm being thrown!"
"Want a brillo pad Scrub?"
"Why do you keep sniping me, scrub?"
"Scrub? This is TFC, n00b".