When u lern korean, u'd better use korean letters. Cuz in those sentences, its quite hard to distinguish the differnce between 'nigga'and 'nikka'. In english alphabet those r almost same sound and look same. But if u wrote those in korean, first one is 니가, and second one is 니까. Those r totally different from each other. 니가 Means 'you are' Talking about listener. 니까 Is sorta expression of honorific language usually put that end of sentence for paying respect. 니가 for example 니가 그걸 해. you do that. 배고프십니까? Are you hungry? I hope this gonna help u up. :D