This word has various definitions and is used to replace certain words.
1).To get crunk
2). When you get screwed or fucked with or if you screw or fuck someone over. Also if you prank or joke someone.
3). If you out do someone or get out done.
4) Giving caution to someone.
5) Etc. Try and use in proper context at your disgression.
1). "Dude we are gonna go to Shakespeares bar and are gonna get nigga'd."
2). "I just nigga'd that motherfucker" or "That motherfucker just nigga'd me."
3) "That guy gets out nigga'd by that fool in drinking" or "Man I just got out nigga'd at singing"
4) "Hey becareful with that hole in the ground, i don't want you to get nigga'd"