Mine happened when I least expected it to, and when I wasn't even trying for it.
Almost the moment I started growing pubic hair, my mound and pussy seemed to itch all the damn time. I would often be told off about sitting in "an unlady-like way", with my legs apart. I wasn't trying to flash or anything, I just liked having my legs open.
Oh, and I was always itching myself down there, either over my clothes or if I could get a hand into my knickers without being seen, then inside, but I never EVER felt aroused or horny by it.
So this day, I was in class, sitting near a window and it was mid-summer. The room was hot and I was bored shitless. I was lolling there in my seat and my legs were spread under the desk as usual. The teacher was one of those who made us repeat endless Latin verb conjugations - as if that would make me learn anything - and we were all droning away.
My hand was in my knickers as I was hot and sweaty down there and it was making me tingle and itch more than usual.
All I remember is that I was idly rubbing my pussy, and muttering the lesson, when as if from nowhere, I thought "Fuck, I'm gonne pee!" As soon as I thought it, a wave of convulsions tore my breath out of me. Blam, Blam, Blam, BLLAAMM.
And I felt something jetting into my knickers. I really thought I had injured myself and made myself pee.
I put my hand up to go to the bathroom, and noticed my hand was wet.
Once in the toilet stall, I lowered my knickers. They were wet through, but not with pee. I remember smelling my own fingers. They smelled sweet and almost like flowers in a way. I looked at the mess in my knickers and suddenly, I knew, I had cum.
Almost straight away, I sat on the toilet, peed and then spread my legs with one hand up under my top and squidging my boob, I masturbated. When I orgasmed, I remember looking down and watching this stuff squirt out of me, but NOT from my pee hole.
Back in class, I found my BFF had put a note on my table. "You fucking lucky bitch!"
Later we talked about it and I told her I cummed in class. She said she often did it and that the squirting would die down after a while.
We talked for ages about boys, fucking, (she had fucked, I hadn't) and she told me about when a boy cums inside you, how it runs out for ages afterwards.
I liked the sound of that and she said next time she fucks her boyfriend she would show me. She did, and that led to something else entirely.