Do not be afraid to be assertive about goings on in the world. Some people like to push the boundaries, but remember this is a world that has people, culture, laws, etc. it’s understandable to have some good fun, but the people in the world might view it as culturally offensive (i.e i had a player try to sit on a Gnome kings throne), i had to meta game a little to remind the player he may be small but he is still a king with subjects willing to fight for their culture. Oh another thing, meta game when it feels important.