What happens legally when you fake a pregnancy?

If the "father" never provided your friend with any money for prenatal needs, then it is unlikely he would be successful if he filed a lawsuit against your friend, as he did not "lose" anything as a result of your friend's deception. Did your friend ever ask for money/things for the "baby," including child support? If so, he may be able to allege fraud or attempted extortion. It would be "attempted" if he never actually provided the items requested. He could file a lawsuit for "pain and suffering," but the standard for that is extremely high, and it usually must accompany some actual injury. For example, a mother may be able to successfully sue for pain and suffering if she saw a school bus run over her child.