Smile in the eyes of your enemies

Is bullying effective if it doesn't bother or harass the person its aimed towards?  The bully is satisfied when your crying, upset or hurt as a result of his insults and violence.  So why not laugh or smile at their insults.  When bullies call you fat, why not laugh instead of cry.    The bullies main objective is to see you upset, don't let them.   As time goes by the bully will realize his juvenile insults have no effect on you, and in turn will stop harassing you.