FOR HIM:

Make up your own erotic tale. Lead him to the bedroom, tuck him into bed, sit by the bed on a chair, and open a book.(any will do, it is  being used as a prop only). then proceed to tell him the dirtiest, sexiest, most erotic fantasy scenario you can bear to say out loud. He's allowed to touch him self but not you. Let him masturbate himself to orgasm as you reach the climax of your tale.

FOR HER:

Indulge a popular female fantasy: sex with a stranger.  Blindfold her. Tie her hands behind her back. Lead her into a dark room and leave her standing alone for a few minutes. Then enter the room stealthily, come up behind her, and tell her you're the handsome stranger who's admired her from afar.  Let it all happen from here.