My first orgasm was in a makeshift diaper. I was about 12 or 13 at the time, in 7th grade. On Fridays I got home from school before my parents were done with work, so I had the house to myself for a few hours.
At this point I had been making makeshift diapers by taking paper towels and stuffing them in my tighty whiteys. I was also using plastic grocery bags as well. This type of play happened any time I had to poop. I noticed that after this type of play a string of pre-cum would always be dripping off my penis but I had no idea what it was.
Anyway, one Friday late afternoon, I laid down on the bathroom floor with my makeshift diaper and pretended I was being changed by the school nurse (I have a medical fetish as well). I imagined her inspecting my penis and I began to touch my erect penis as if I was a medical nurse examining it. One thing led to the other and the next thing I’m gripping it and moving up and down and all of the sudden…..boom! Cum shoots out and I’m laying on the floor starring at the ceiling in a state of shock. I eventually come to and realize “this is what an orgasm is, holy shit!”. I was also still laying down on that makeshift diaper too.