HUMAN ACT. An act that is performed only by a human being and thus is proper to man. ... When a human being does such acts, they are called acts of man but not human acts. Acts of man, therefore, are acts shared in common by man and other animals, whereas human acts are proper to human beings.
It means that even it everyone is doing something wrong, it is not right. It is referring to peer pressure, don't do something just because everyone else it doing it.
