You don't even know the dark thing that live in my mind

I have told people this before then I tell them that "they don't even know the dark thing that live in my mind". People shut up really fast. Also good is if some one yells "fuck you" I smile really big and say "fuck you to" like I just said "good to see you". People don't know what to do. They loss all their power over you if you don't get mad. Other things that work well are "ok", "tell me something I don't know", and "good to know".