I guy or girl that has no personal hygiene, very ugly or awkward face. Greasy. A person that keeps to themselves and does weird things. Walks funny, or generally screwed up
EX1/Person one:"Dude did you smell that guy's BO back there."
Person two: " Yeh what a scrub"
Ex2- " god he has been acting like such a scrub lately"
a scrub is a guy that thinks he's fly, also known as a busta. Always thinkin' 'bout what he wants and just sits on his broke ass. Sittin' in the passengers side of his best friend's ride, trying to holla. If you don't have a car and you're walking, you live at home with your mama, and/or have a shawty and don't show love, you're a scrub/busta.
A person who has clocked over 200 hours total on football manager games and has bought many gems on smite. They tend to like to talk about plot of a tv show you watch because they are fuckwits.
Person 1:"Hi sam!"
Sam: "Hey, here's some spoilers on Arrow"
Person1: "Sam is such a Scrub"