A frequent utterance of Bart Simpson, "[Don't have a cow]" dismisses the other person's feelings as overreactive to the situation. The person who expresses anger, shock, disgust, or any of several other negative feelings towards an action or person is seen as having a cow. The person who induces [bovine delivery], either through doing it or telling of the activity, often tries to minimize the activity as something not so bad. Saying [don't have a cow] minimizes both the activity itself *and* the person's feelings who is having the cow.
Sean Ward
Because he has to do something in his free time
