When about 11 or 12 I got really constipated and was given a mighty enema from a Rexall Roxbury bag by a visiting nurse, which I've described in other posts. For this enema, I was laying flat on the bed on my tummy. I don't remember whether I had an erection or not.
This experience must have made a deep impression on me. Sometime thereafter, I went looking for what I then thought was the hot water bottle that had been used on to make me poo, searching clandestinely when my parents were out. Eventually, I found a long, flat, blue box in the bottom drawer of a bureau with some of my mom's stuff on top of it
At the next opportunity, when my parents were again out, I took the box into the bathroom and locked the door and examined the contents. It was not hard to figure out how it all went together and assembled it and filled the bag with warm water and dropped a bar of Ivory soap into it for a couple of minutes. I remembered the scent and whitish color of the Ivory from my prior experience.
In that bathroom the medicine cabinet was pretty large and I hung the bag from the cabinet's doorknob, and swung the door out so the filled bag was hanging about 4 to 5 feet above the floor. I then put a bath towel on the floor, got undressed, and laid flat on the floor on my tummy as this was the only position I knew about, and inserted the black, hard rubber nozzle.
As I lay there filling, I suddenly had what I later learned was an orgasm and ejaculated on the towel. At the time I had absolutely no idea what had happened I let the enema continue to flow into me and then got up, sat on the toilet, and had a strong poo Of course, I eventually found out what had happened and that the whitish discharge from my penis was entirely normal.