I was staying over at my grandparents house and already been getting erections for a while, I'd already tried jerking a few times previously but as the pressure built it became too intense and I'd stopped.
This particular night I must've decided to carry on jerking, I remember I had a local radio station playing in the background on an old MW set in the bedroom which played mediocre popular music.
I can remember squirming while jerking from the intensity of the pressure building and had a t shirt in my lap to deal with the flow of precum, however, I wasn't prepared for that release. I must've drove on through the pressure and can still remember my cock exploding as I went into orgasam, I'd let go of myself and the feeling was so intense I was writhing on the bed while my cock was out of control pumping out a huge load. I lay there afterwards for some time basking in the amazing feeling of the release before the reality sank in that I had an awful lot of cleaning up to do, I tried cleaning up best I could before getting interrupted asking what I was doing.
I think I made up some crap about being sick but it didn't really work, they must've knew what I'd been doing.