Underwear shopping

After the lesson ends you head to the local mall to do some shopping, you pick a few crop tops you like and then you notice the lingerie section, you've never been the girl to wear lace panties, but you are open to trying. You go through the wide offering of panties and bras, finally you pick out a flimsy g-string and a very see-through bra.

You are about the enter the changing room to try on some stuff, but a clerk stops you
"Excuse me, by store policy you can't bring underwear into the changing rooms"
"How am I supposed to know if the fit then?"
"Just eyeball it I guess, I'm sorry I think it's a theft-prevention rule"
"I'm not going to steal them, just see if they fit!"

The clerk wasn't convinced, so you try to leverage his weaknesses

"You can verify it yourself if you want, I'm not shy"
"Ehmm, what do you mean?"
"I could leave a door open, so that you can check I'm not doing anything shady"

He looks around at the empty shop and finally agrees "Ok, but I must have full view at all times, you know ehm to control that nothing shady happens", "Of course" you reply.

You get into the stall and take off your shirt to try on the crop tops, you make sure that he has a nice view of your C cup boobs squeezed in your bra. You are deliberately slow in trying on the two crop tops you have chosen, then you move on to the bra: you remove yours and leave your boobs hanging for anyone to see as you pickup the lace bra. The clerk clearly has a huge boner as he sees you wrap your tits in the bra, you turn back to him and ask "What do you think? Too revealing?", he blushes "I think it suits you, it's very ... charming". You decide to move to the main bit of your show: "Could you enter the stall so I can have a little privacy while I try the panties?", his boner is now straining against the button "Yes, of course".

As he closes the door you face the mirror and drop your shorts, as you bend down you push your bare ass against his crotch. You pull up the g-string, it's so thin that you pussy lips easily grab it from either side, the little cold beads on the crotch tingle your pussy. Finally the clerk musters some courage and grabs your hips "Very fine choice, not many girls choose such small g-strings".