"Poor you" use
Person 1: I failed a test
Person 2: Naww

To say no use
Person 1: are you gay
person 2: naww im not

To say something is cute or to say the other person said something cute.
Person 1: I love you
Person 2: Naww i love you too

Person 1: "yo, u goin out tonight? we're gunna get hangin yeh?"

Person 2: "Naww, CBA."

Man 1:Dude spend 20 dollar on some chip and spill that shit in the street
Man 2: jail nawww.. that shit crazy