A certain tribe in a valley believes that the soul remains trapped in the body after death and is aware of it. So they treat their dead as if they are alive, talking to them and keeping them at home. They are used to the stink and for some reason are also immune to the diseases that this practise causes but outsiders are not so lucky.
An army and navy who work in the same way as others except their rank titles are upside-down. So people start as full generals and those with the rank of private command armies.
In a deeply unsettled world, much of it anarchistic or ruled by murderous gangs, a group have adopted the armour, weapons and discipline of an army of the distant past.
What if casting magic changed (for a few hours or days depending on the strength of the spell) the colour of the skin of the spellcaster? It could lead sadly to a very racist world to rp in.
A certain patch of forest is well known for causing anyone who ventures into it to suddenly go blind. Once they leave the area their vision returns. Rumors of treasure hidden within.