An idiom used in the 90's. It means to masturbate. Nigga means your penis, jigga means to jiggle it.
Peter:What the fuck are you doing?
Robert: Can't you see what I'm doing?
Peter: Just tell me.
Robert: Jigga my nigga, what else do you think I'm doing while I'm watching porn?
Robert: Can't you see what I'm doing?
Peter: Just tell me.
Robert: Jigga my nigga, what else do you think I'm doing while I'm watching porn?
by Vasu C. June 6, 2010