21st Birthday wank by a stranger

So this was my 21st birthdayy and I went out with my friends, had a good time and I was on my way back, I was a bit bi-curious at this time.

I took the local train back in the evening and it was pretty crowded. I was standing amongst the crowd and there is exactly when I felt someone's hand brush past my crotch, I felt a tingle in my body, I kinda liked it I guess? This guy looked well into his 30's and a bit strongly built! I thought it was an accidental brush but a few seconds later, the guy brushed past my zip again and I felt a bit aroused now, he sensed it too!! He started brushing his hand near my zipper after, I got a bit erect, it was normal pants and not jeans! He then slyly unzipped my fly and started brushing his hand against my underwear, and felt my cock! My cock was feeling it now, but since it was on the train , we had to frequently adjust ourselves. So he never fully got it out, but was feeling my cock up through my underwear, started rubbing it and giving my cock a few small strokes, I was throbbing and I actually came in my underwearr so fastttt, sighh..... he felt the wetness of my cum in my undies and took his hand out. I had mixed feelings at the time lol.

He then looked at me, took my hand and started brushing my fingers against his pants, I actually felt his erection. I was a bit scared to like go all in, in public, and I wasn't so sure myself on what I was doing.. so i was just casually brushing my hands against his dick, he then unzipped his fly and pulled my hand towards his dick, I hesitantly gave it a few strokes and started growing into it but then the stop arrived, a lot of people had to get down and we didn't have that many people in between us now, and that was kinda it as he got down at the next stop too! I kinda felt bad that I did not repay the favour but it was my first ever sexual experience if I may say?... I am 27 now and still think about it sometimes!