If the parents are giving a friend their child how can the adult accepting the child become legally bonded so the parents cannot take custody of the child at some future time?

Parents cannot "give" a child to someone. All parties must follow the required adoption or guardianship procedures according to the laws of the state and through the appropriate state court. Taking arbitrary action concerning the custody of a minor child can create serious legal complications and potential criminal charges and other penalties for all parties involved. In such cases all participants are required to retain legal counsel. In most cases the court will appoint a Guardian Ad Litem to represent the child's best interest.