keep going

You try the next changing room and find a young woman trying on a t-thong and seeing how her butt looked in it. You do you routine of having her not see you or notice the door open, so she continues to check out her ass

She will freeze and be unaware of what's happening to her. You then expand her hip an inch, expand her butt out by two inches, firm it up, and shave a half an inch off her waist.

She will not notice any changes to her body. She will think she is fully dressed. She will pay for the underwear she has on thinking she is wearing her clothing over it. She will think the clothes on the floor were just an extra set she brought in. She will not realize she is wearing only underwear until someone outside the store points it out. Once she realizes she is only in her underwear, she will grow very ashamed but very horny that people got to see her bare ass cheeks.From now on she will crave spankings during foreplay and crave being fucked ass up face down. She will need that to happen tonight and at least twice a week from now on. If she is on her period, she will take it up the ass.

You let her move.