Spontaneous orgasm - very weird experience

I just had one of the weirdest experiences of my life. I'm posting this using a throwaway account.

First, some background. Since I was a kid there's been a type of situation that produces a sexual, tingly sensation in the tip of my penis. The best way to describe the situation is if I'm doing something I know I'm not supposed to be doing, and I could stop any moment, but I keep doing it. Another way to describe it is pushing the limits of getting away with something.

I remember one example from around first grade that used to produce this sensation. We'd be outside at recess playing on the gym equipment. The teacher would call out to us that it's time to come in. Most of the kids would immediately stop and head in. A few kids might keep playing a few moments before heading in. Waiting a few moments was no big deal, but if you waited longer the teacher would call again to you to come in.

I started noticing that if I pushed the limits of how long I kept playing, I'd get an tingly sensation in the tip of my penis. I didn't recognize it as a sexual feeling. I couldn't then (or now) decide if it was pleasurable, but it was (and is) very intense. So I did a few experimental tests of seeing how intense it would get the longer I kept playing. I remember one day all the other kids were lined up, the teacher was calling to me, I was still playing. The sensation was almost overwhelming.

Since then I've had it happen from time to time, though not very intensely. Adulthood just doesn't seem to produce the situation that triggers it. Until recently, that is.

It happened big time on my part time job a few days ago. I don't want to get into too many details lest somebody recognize me, but here's the general idea. I was driving along on my job, and I was definitely pushing the limits on something I was getting away with. I started getting that sensation in my penis. But unlike when I was a kid and pushed the limits for a minute or two, I kept at it for hours. Add to that, it was near the end of my shift and I was very tired... I'd been on my day job first, then my part time job.

For the first few hours I didn't think much of it... I recognized what it was and didn't perceive any issues from it. But it kept getting more and more intense. Finally, after about two hours, it was like someone was frantically masturbating me. I realized I was headed towards an orgasm. I tried to calm myself and ignore the sensation, because I didn't want to cum right there in my pants. But it was like when I try to hold off an orgasm during sex... it just doesn't work. Realizing the inevitable, I grabbed some napkins and shoved them down my pants. A minute later I had a massive orgasm. I mean, I was screaming and shouting "Oh! Oh! Oh God!!!" If I wasn't so weirded out by the situation I might have enjoyed it.

I was glad I was alone in the car. I'm not always.

So this is one of the weirdest things that's ever happened to me. I've had spontaneous orgasms in my sleep before, but never when I was awake. I wonder if it will happen when I drive next week (and probably push some limits).

Anybody ever experienced anything like this?