She finds another pair.

You watch as Katie flips through different pairs of underwear. You hope she changes you back, you can feel the fabric of your panties with every movement. Worse yet, you’re starting to like it. After walking to the other side of a display, she picks up another pair. You gulp. “What do you think?” She asks innocently, holding up a black thong. She giggles as you feel another shift. This time you felt the fabric on your rear become tighter and tighter, until the thin cotton strap slipped in between your ass cheeks.

“Y-you can’t do this to me” you beg her as she continues to look through underwear.

“I can’t?” She retorts, “say, what do you think about g-strings?” You gulp once again as you feel your thong begin to shift. The strap gets thinner until it feels like you are wearing virtually nothing. A mere triangle of fabric covers your junk, and a string rides up your ass.