...I never understood the panty stealing cliche. Especially in the days of internet porn. She's not even shy and already went a day without, so why bother?
I absolutely love it when women go without, sure, but that's a piece of clothing that can accentuate the prime objective in so many different ways.
Another way to go about this without potentially ruining her own clothes or having a weird gathering of panty-obsessed men is the modeling job. She got free clothes from there, I think. They could just not fit her quite well. Too small, too big, she's not experienced with certain ties'n'bits, lots of things can be done if she were to be frivolous about it.
Although I'd be wary of focusing on wardrobe malfunctions too much. It can easily come off as more silly than sexy. That is unless the intention is slippage.