A bitch ass nigga is a person who talks/ acts all tough online but is a pussy ass bitch in person. This is a person like soulja boy, a person who can talk shit but not back it up in any way.
Man 1: aye, you the nigga who be talkin shit bout me, so whats up then pussy
Bitch ass nigga: nah that aint me, you know its all love over here
Man 1: Oh so you just a bitch ass nigga, i see how it is