this happened to me today.
me and some friends went to a gym close to my house to use the squash courts there. We do this every few weeks now, the squash courts are located on a lower level and there is an observation area upstairs. I was sitting on our court having a rest while the rest of my friends were getting dressed and I looked up and saw this beautiful girl sitting down at one of the tables near the handrail. I kept looking at her while she talked to her friends, she was wearing a short checkered skirt with a white polo on, she looked about 19. She had brown hair down to her shoulders and was tan and very pretty. After staring at this beautiful girl for a while she finally got up to get something out of her purse that was next to her chair, she bent over facing away from me and i saw directly up her skirt at her near perfect ass in a blue thong that made her ass look amazing. I got a great long look up her skirt while she dug around in her purse for a good 5 minutes, i could see her blue thong going along the bottom of her pussy and into the bottom of her ass cheeks. Her ass was perfect, one of those great muscly ones and the way she was standing made made her left ass cheek overlap the right one a bit. looked a lot like the attached photo. Sadly though she got up and left with her friends but it was the best upskirt experience i have ever had......for now