A Social norm is also a set of behavioral models and rules that are assimilated within a society.
That is why we call other people "weird" because they don't fit into society's definition of normality. Some people think social norms are ridicules because no one is "normal", society just claims that everyone should act like so to be "normal".
I personally think social norms are useless because otherwise we would all be the same in every way, just followers in society.
