Once you pop, you can't stop

You yawn, and as you do so, Lauren stretches her arms behind her head, closes her eyes, and yawns. This action pushes her chest out, and another button pops off, giving David a view of more of her bra. He blushes, and you can tell he is becoming aroused.

Lauren sighs and smiles at David. "Sorry, don't know why I'm tired. Maybe I need a refill of my coffee." She gets up, still unaware that two buttons are gone from her blouse. She reaches for her purse to get some cash.

As Lauren reaches, she is next to David with her back turned slightly. Thanks to you, there is a loose thread hanging from the seam of Lauren's skirt. The seam runs down the middle of the back of her skirt. David reaches up to grab it and pinch it off, but as she grabs it, Lauren turns on heel and walks to the counter. As she does, the thread continues to unravel from her skirt. David keeps pulling, hoping the thread will break, but instead, the seam on the back of Lauren's skirt pops open, exposing her lacy white panties. As David tries in vain to break the thread, it just unravels more, and the seam splits wider and wider until it runs from the waistband of her skirt to below her butt.

Thanks to you, Lauren's blouse is tucked into her panties, so they aren't blocking the view you and David have of her panties.