I was still at school when this happened but can still remember it clearly because I relive the moment often enough in my fantasies. I was sitting in class one day and we had this hunk teaching us Latin. He had a weird surname, I can't remember what. What I do remember is that I was getting wetter by the second watching him write on the board and fantasizing the dirtiest things you can imagine a schoolgirl having.
I just had to get off. I asked to be excused from class and was glad not being male for my pants would have given away the fact how horny I was. I walked to the toilets and chose the stall furthest from the door. There were only three and the one in the middle was already occupied. I locked the door and hiked up my skirt. I didn't want to waste time cleaning the seat, so I just leaned up against the wall. My backside was against the cool paint, my feet wide apart and both my hands in my panties.
I rubbed myself hard, feeling my fingers slipping in the wetness, spreading it all over my fanny. I flicked my clit every so often and could feel the orgasm building. I was about to cum when I heard a sound. I opened my eyes and looked up. A head was peeking over the partition. It was a girl who was younger than me. When I looked up she ducked down, but I had already seen her. I didn't know what to do, so I dropped my skirt, flushed the toilet and went back to class.
That night and many thereafter, I jilled myself while reliving that episode, but with different endings. I saw her once or twice after that, but never could figure if she recognised me.