Stands for 'Niggie Nig' in reference to a black person. Used in a respectful way by young naive white university students who wish they were black for a day
Dr. Dre:
"who d'u think brought u the O.Gs,
Eazy-Es, Ice Cubes and D.O.Cs
Snoop D-O double Gs, (s-n-double-o-p-d-o-double-g)
And the group that said muthafuck the police."