A gym workout

Leaving the shop you see the half empty gym in front of it and you get a mischievous idea. You enter the gym and at the counter you find Amber, a young blonde girl wearing a white dress with a deep cleavage, surely chosen to draw males in, but it did help in convincing you too.

"Could I do a trial session with a personal trainer?"

"For sure, when would you be free?"

"Right now would be best"

"At the moment there is only me in the gym, but I'm a personal trainer too, so I just need a moment to change outfit and we can start"

"Great, do you by any chance have some gym clothes to lend me? I forgot my gym bag at home"

"We don't usually do this, but you seem to be about my size and I have a spare outfit, so you are in luck"

She then shows you the changing room and hands you a white outfit with a sport bra and a short training skirt with pants underneath. Amber starts changing right next to you, you turn your back to her and lift up your red dress. You take your time folding it and putting it in the locker so that she can have a good look at your bare butt and at your sideboob, judging from the fact you don't hear her dressing she probably liked the view.

Then you turn and walking to the bathroom you glance at her phone, you can read part of a message "...fuck that ass..." under what looks like a hastily taken picture of your butt. Seeing that the attraction is reciprocal you choose to tease her a bit more: in the bathroom you tear a small hole in the pants right on your pussy, just big enough to slide a finger inside (you checked yourself).