social norms
By nature, humans can’t help constructing rules to live by even in the most innocuous situations like choosing the passenger seat of a car (rock-paper-scissors: best of three). Without any official governing body over how many times you should let a phone ring before hanging up (seven), we are left to establish unwritten social rules naturally agreed upon and often followed to the letter.
A survey by MyNavi recently asked Japanese people which of these tacit rules should be called into question. As we will soon see, although these laws are mysterious in their origin, many of them tend to be quite practical and worth sticking to.