Games
To know if someone can speak offensively or politely, don’t give him poem to recite; don’t give him a song to sing. Just engage him in an argument and you will know it for yourself who he is.
Talk to strangers politely... Every friend you have now was once a stranger, although not every stranger becomes a friend.
It is unpredictable for you to know which of the strangers you are about to meet that becomes your friend. Be polite to every stranger!