I have a few train experiences to share
I talked previously (see link) about travelling on trains with separate compartments that could not be accessed or seen into apart from when the train was in a station.
Many times on my way home from college I would get an empty compartment to myself and have an enjoyable wank when the train was between stations.
Sometimes the train would stop at red light signals before being allowed into the next station. One day this happened and I took the chance to have a longer slow wank while the train was stationary. I was really enjoying gliding the foreskin up and down over the head of my very hard teenage penis that was poking through the fly of my school trousers. Suddenly I heard laughter and looked up. I had been so into my session that I had not noticed that another train had stopped on the adjacent line and people in a carriage on that train could see directly into mine and what I was up to. It was a couple of teenage boys by the window that were laughing and pointing but there were two or three adults in the compartment too. One of whom had stood up to see what the boys were laughing at.
I recall being overwhelmed with embarrassment. Red in the face and very hot. Flustered I didn't simple cover myself up or turn away, but instead I clumsily stuffed my still erect penis back through the fly of my trousers.
I looked up again to see the two boys (who fortunately I didn't know) laughing uncontrollably. Luckily my train then started to move again.
I was more careful from then on but I had many more train adventures.