Green’s Dictionary of Slang

(orig. US black) a greeting.

1991		Eble Campus Sl. Mar.
1997–2000		Da Bomb 🌐 12: G: 1. Replaces someone’s name. What up G?
2002		Teen Lingo: The Source for Youth Ministry 🌐 G n. (derived from ‘Gangster’) A name for anyone you would associate with. A name when greeting a friend. ‘Whasup G?’.