A Asshole on Xbox Live that decides to sale all his shit because he is a dumbass, then buys it back just to one up you all the time in whatever game you are playing.
Dude 1: WTF man how did you get on the leaderboards so high!!! You haven't even had a Xbox for like 5 months!!!
Dude 2: What can I say I guess I just have uber skillz and 1337ness.
Dude 1: No your just a fuckin Goo Monkey thats all!!!
Dude 2: Take that back mother fucker NOW!!!!!!
A silly old Eastern-Indian slang for a person who annoys their siblings like a Monkey and generally it is the younger sibling who annoys the older one and hence the prefix is immaturely stated as 'Goo' defining childish and often juvenile.
Hey look at Pongoz, He's pestering his brother like hell. He's such a Goo Monkey.