I was around 12 years old when I had an orgasm due to very high stress. Thought my bike was stolen and going up and down the street to look after it, suddenly a strong arousal appeared in my genitals and a strong dry orgasm. And a few minutes later, another one, on the same anxiety and stress.
After a few more in a raw, a became scared about what is happening to me. Tried to stop somehow the next orgasm by stretching my penis gently. But you can imagine the next orgasm was unstoppable.