When I was in 12th year ( 17 yo and final year ), we held our annual 'walk for health' event which we initiated when I was in 10th year. My buddy was the president of the health club and I was the coordinator. We often divide the school into 2 groups and send each group on a different trip. we sent year 7,8 and 9 to a beach picnic walking. Year 10,11, and 12 on a mountain hiking trip. Well it was a design track, not just something random. Most interesting part of it, most male teachers were sent with the kids since they needed more supervisions. We took most of the female young teachers to the mountain hiking.
One of the teachers, a 29 yo tiny short lady probably less than 110lbs was having a tough time climbing up and down where the track had obstacles. She lagged behind with my buddy(the president) helping her out getting up and down boulders and I was just a few meters in front of them with 4 buddies chatting along. She was nothing hot or attractive and just chatty. At about halfway, he was probably fed up and asked me to take his place for a while. Seeing the teacher's distress face, I could not say no and just took his place. I was wondering why on hell did she wear jeans to a hiking trip. She probably had no idea what awaited her. At some point as she was moving down the boulders, her jeans was lowering on its own though her T shirt had it covered. Then we approached a place where we had to jump off a 4 feet high rock and she was scared to do so. My friends kept going as I awaited on her to do so. She tried to crawl off it but refused as she nearly lost her balance. I finally asked her to sit down and I'll take her off it, and as I took off her by her thighs and putting her down sliding off my fore arms, I felt her bared ass skin and her face expression changed from scared to shy in an instant. She stood frozen and from scared to shy and quiet. I told her in a hurry, 'I think your jeans is falling off'. she smiled and picked it up and as she did so, I caught a glimpse of her thong. We continued and caught more views as she kinda let her guard down since we were a bit behind everyone. I never told anyone at school about it.