This happened on Monday.
It was the end of a long day, and I was in English class. I had been feeling increasingly horny throughout the lesson and, as we are studying Of Mice And Men, our discussion about whorehouses and prostitutes had not helped.
As soon as class was over I RAN to the toilets, went into the end cubicle, locked the door and sat down. I slowly started rubbing my clit. Hearing voices outside the window (the toilets are on the first floor) only made it more exciting. Suddenly I felt myself on the edge, and rubbed harder, and faster, until I brought myself to a very satisfying climax.
I then flushed the toilet, washed my hands and went off to choir practice as though nothing had happened. I doubt that this will be the only time I masturbate at school!