Its a word refering to the word nigger, a racial slur to often agitate black people.
Oh man, look at that nig-nog!
Funny way to describe a black person without saying the "N" word.
Look at what that nig nog is wearing, he looks like he stole his big brothers clothes and is wearing them. I know, why do nig nogs always want to wear shirts that look like night gowns?