You really love the idea of messing around with Kristen, and you really enjoy being her panties, so you decide to stick with what you're already doing, with the hilarious exception of making yourself even smaller and tighter around her smooth body. It's a great idea, but you'll have to time it right: since Kristen is already running to the bathroom in a panic to figure out why her panties are suddenly eating her out, you'll want her thinking everything has gone back to normal the minute she goes to look.
You can't see much as Kristen's panties, but you can see her legs and the ground below her skirt. You watch and notice the linoleum floor of the hallways turn into the checkered tile of the bathroom and you know it's almost time. You hear a door open on a bathroom stall, and then Kristen turns around and sticks her thumbs under her skirt and panties on each side of her hip. She's about one second from pulling down her panties and seeing the tongue right on her crotch. At that instant, you concentrate hard: you want to become exactly like her silk green panties were before, just half a size smaller.
It works. Or, so it appears. It's hard to tell as Kristen lowers you down past her knees and stares at you in wonder. The tongue is gone, and you feel a little smaller, but right now you're just amazed at the sight of this girl Kristen, now a giantess, staring down at you with no idea that her panties are a fully conscious, living being, who she already knows. This is exactly what you signed up for, and the look on her face of simultaneous frustration and confusion, looking for a wet tongue that she knows she felt but just isn't there, reminds you yet again that you made exactly the right choice in choosing to become Kristen's panties for the day.
Kristen, for her part, really seems to have no idea what's going on. She definitely felt a tongue licking and sucking her clitoris, in the middle of class, for an extended amount of time. Her panties look normal, and she feels her crotch to make sure there's nothing wrong there. Although her pussy is still soaking wet, it otherwise seems normal. She's so confused. But, failing any explanation, there's not much she can do, and she's got to get back to class. Kristen pulls up her skirt and panties and walks back to class.
For you, of course, the experience is amazing. You're gazing back at your beautiful owner as she stares down at you bewildered, and then you see her reach down her giant hand and start to feel her clit for a moment. It's a terrific experience, but it's even better when she reaches down and pulls you up. You love the way it feels when Kristen's enormous hands pull on you and squeeze you against her nether regions, and this time it's even better. Kristen appears in too much of a rush to notice her half-size smaller panties, but it doesn't escape your attention: everything about the experience has been heightened. Your waistband now digs into Kristen's hips, your leg holes now more snugly hold onto her fine ass, and you find your crotch area tightly wrapped around Kristen's beautiful pussy lips.
Kristen walks back to class and sits down. Though everything's tighter, and you have a hard time imagining she hasn't noticed her smaller size yet, even if there's not much she can do about it while she's sitting in class, Kristen seems not to have a hard time walking or sitting down. At least not at this size.