Here’s how it works:
My name is Nick (known by most, but not the stray reader), spelled 닉. Theㄱ sounds like a blend between K and G. When a close friend is talking to you they add 아/Ah to the end. So we have Nickah, i.e. Nigga. I found it a bit offensive when my girlfriend starting calling me Nigga, but what can I do? it’s my name, 닉씨/Nickssi is too formal and 니콜라스아 is too long.
Koreans have their own racial slur for black people, which is 깜둥이. The equivalents for whites/crackas is 흰둥이(hin-doong-ee). 둥이 is usually reserved for kids. For example, 팔삭둥이(pal-sock-doong-ee) is a term for a premature child, literally a baby born in the eighth month of pregnancy. There’s no 노랑둥이 though, which would be the equivalent of yellow/gook.
It is believed by some that Gook is derived from the Korean ending 국, which means country. As it goes, American soldiers thought 미국, the term for America(n), sounded like “me gook”, i.e. “I am a gook”, which became a general racial slur against all Asians. Click for an extended article on the subject.
I didn’t expect to look that far into it since I’m not the type to use such terms, but it’s nonetheless interesting to know the etymology. I am grateful to my coworker 봉영/Bo Young, who helped with some of the Korean terms, specifically those in the second paragraph.