Have a private party with some of your Dom friends. Simply have your sub serve drinks and snacks on a silver tray. She is of course naked with perfect makeup applied and wearing her collar. She is instructed to allow anyone ( male or female ) at the party to do anything they like to her. Do NOT tell the guests. Then you may observe how bold they get as the night goes on. You may punish her later for any slow service or for being a slut who allows anyone to have her, etc.