Romans 12:14 in the King James Version reads, "Bless them which persecute you: bless and curse not."
I know that is going against society, but think about it. If you do something nice for someone who was just very mean to you, you are showing kindness and forgiveness (which is God's will for us) and this, most likely will irk them that you have the capacity to be nice after they are mean. Romans 12:20 reads, "therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head." Luke 11:13 reads, "If you then, though you are evil, know how to give good gifts to your children, how much more will your Father in heaven give the Holy Spirit to those who ask him!" We need to be fishers of men and lead a Christian life. Living Romans 12:14 is another way to do that.