I live in Sweden and it's pretty much the most informal country in the world. Students call teachers by their first name and sometimes little kids joke about calling their teacher mom which would be considered extremely rude in countries like Japan. At work we address our boss by first name and everyone is equal.
We don't even invite guests for dinner, which is the opposite in South. I had to wait in the living room as a kid while my friend was having dinner.
How formal is your country and do you have any customs?