Taboo is something that is prohibited by the customs/norms of society and is considered social deviance… not something that’s ordinary. So Keisha hitting the backseat in Keisha’s song becomes a taboo. Before people around that would just be like “yeah ok” but now that he makes a song about it people distance themselves from it and look down on it like he implies he does.
He’s saying about how the boy will think its normal for sexual encounters with priests, maybe just all older men in general, and maybe the child doesn’t even think of it as a sexual encounter but more as a simple occurrence because he doesn’t really know what is going on.
Payback is a bitch, and the bitch has been living in debt with him so therefore because payback is a bitch so the bitch is his because the form of payback is a bitch. Maybe?