Apart from wet dreams, anyone spurted their cream without masterbating? My experience:

Sitting on a park bench had my hard cock out of unzipped shorts, my t-shirt not really able to cover it. When someone happened along the path I casually placed hands on my lap - the only time the erection was touched.
Then I saw a whole group of folk walking towards me. Oh god... so exciting I was going to cum. I hastily grabbed my rucksack holding it in front of me and walked off. The climax subsided - thankfully as I didn't yet want the adventure to end.

I first found this daring to be seen giving me the same fab feeling as wanking was years before. Had to get a bus home from work. I went to the unoccupied back bench and next to the window I unzipped, revealing large bulge sticking up under loose white underpants.
Sat there, excited as people got on and off the bus at various stops. Someone came towards the back. I just spurted soaking my pants and balls. Happened I was wearing a coat that I could button up when I reached my stop to get off.