This might pale in comparison with all the other replies here, but one incident really made me uneasy.

I was seated inside a train minding my own business. I was wearing a loose shirt and an even looser pair of walking shorts. The shorts were made of thin and glossy material. It wasn't thin enough to expose my underwear but it readily shows any bumps or whatnot.

The train wasn't that full, and there were lots of empty seats. The train had longitudinal seating (two rows of seats facing each other, with some standing space in between. There's also an area where the train can "bend". This area has no seats of course. I was seated next to this "bendy area".

I remember having difficulty staying awake and was seated in an increasingly loose way. I caught a glimpse of a guy standing in front of me. He was leaning against the train walls and was on his phone.

Now, the train isn't the most quiet, but I distinctly heard an unmistakeable camera sound which jolted me awake. Selfie cameras on phones wasn't yet a thing back then and the way his phone is oriented, I can see the phone's camera lens pointed at me. The guy, noticing that I noticed the sound, quickly put the phone back in his pocket.

I might be wrong, I hope I was wrong, but I thought a stranger took a photo of me just a meter or two away from me.

That's it. Kinda underwhelming, I suppose but I was kept wondering why that guy, if it's indeed the case, took a picture of me.