Green’s Dictionary of Slang

(US black/campus) dressed in the style currently favoured by black urban gangsta n. (1) youth.

1990		Eble Campus Sl. Nov. 4: g’ed – well-dressed.
1991		L. Bing Do or Die (1992) ix: Teenage boys and young men in their early twenties were [...] ‘G’d up.’ Shorts, jackets, baseball caps, ninety-dollar running shoes — everything in the same bright, aggressive color.
1997		G. Sikes 8 Ball Chicks (1998) 10: It took them hours to get ‘G’d up,’ or gangster dressed in Crip blue.
1999		Dr Dre ‘Let’s Get High’ 🎵 I make the four hop pull up at the spot / Weed by the barrels in my G’d up apparel.
2001		Snoop Dog ‘Bring It On’ 🎵 I stay G’d up / All the G’s from my set ain’t never P-C-up.