I was really surprised in Rio de Janeiro when in a bookshop I asked "Do you have X book?" and the owner said "Pois não!", left and returned back immediatly with the bok I was asking about. A direct translation into Spanish, my mother tongue, is "¡Pues no!", a quite rude and evident way of saying "No, I haven't". Apparently, in Rio that "Pois não" means "Of course!" or something similar. I've noticed that is used also when the deskman first addresses to a client: "¿Pois não?"

Can somebody tell me if is just in Rio de Janeiro, or if this happens in all Brazil? Also, somebody knows why?