Greebo has been disused in many ways, now it means to be somewhere between goth and punk, usually listens to metal/punk/rock WRONG!
The traditional meaning of greebo:
Split the word
Gree - bo
Gree - Greasy
Bo - Biker
Greebo- Greasy Biker
so therefore a greebo is a person who loves their motorcycle and spends hours tuning it and gets greasy in the process.
Townie: Oi ya f***in Greebo!!!
Unsuspecting Punk/Goth: WTF!
Townie: Yeah! You! F***in Gay BOI!
Greebo: *rides in on Harley Davidson* I'm The only F***in Greebo here! Now Pi** off ya sill T**T!
Townie: AH! NO!
Unsuspecting Punk/Goth: Erm... yeah... okay...