You enjoy spending the rest of the class period digging into Kristen's body around her pussy. She's obviously uncomfortable, and you enjoy making her squirm around as she tries to find a tolerable sitting position. The best part about being so tight is that you really feel like you're completely embracing her pussy. It's a fun experience.
You wonder for a while if she's going to just get up and leave class, but she manages to tough it out. Once the professor ends her lecture, though, Kristen is up and out of there faster than anyone else in the class. She rushes into the bathroom and almost rips you off her. You're crumpled up a bit and then thrown into her backpack. She zips it up and you're surrounded by darkness as Kristen heads back to the dorm room.
After a few minutes of bouncing around in Kristen's bookbag, the motion suddenly stops. You've taken the moment to appreciate just how beautiful your situation is: you've become your hot friend's panties, and you're all crumpled up in her bookbag after she's worn you to class. Really could be worse. But when she puts her backpack down, you're shaken out of your reverie.
She then opens the backpack and you see her giant, beautiful face look down on you with concern. She's obviously figured out something strange is up with her panties, and she seems intent on figuring out what.
She pulls you out and stretches you out. She looks at you closely, trying to notice anything funny. You enjoy the experience of having her spread you out and look so closely at you. You look right back, although she has no way of knowing that.