[Enlil]

Two ideas:

If it´s not too hot or too cold where you live: take her for a walk in nothing but a coat and shoes.

Take her to a coffee shop or a restaurant; she has to wear a very short dress. At some moment tell her to go to the ladies room and take her panties off. Then she has to go back to your table and hand them over to you. She can be discreet about it but she cannot put them to her bag or anywhere - she has to parade through the restaurant with her pants in her hand. And once she comes back and sits down she´s not allowed to put her legs together. Choose a place so that she will be as exposed as you want.