Clamp her nipples.

You're not above inflicting a little pain. It takes you a while to find the right kind of speciality shop, but soon enough you're back with two small wicked brass nipple clamps, small heavy bells attached to them by chains. You place one on her stiff left nipple, one on her right. You flick the bells and they jingle back and forth, making a pleasant noise. If she wiggles around at all, she'll attract attention.

So much for that. Now you have some thoughts about her panties. You like the feel of the tight, red, silky garment, and you can think of a few interesting uses for them.