Is it a dream or an actual event. If it was real then u need to get out
if it was a dream it could be just your subconsience trying to work the
crap out of what his sister said. But u need to look at the facts what
kind of sister would joke about having sex with her brother? That is
just gross. I would bale. That is just wrong. There is something wrong
there. And he might be. There is only three people that know the truth,
That is God and them.