It was my most memorable moment on public transportation so far. It happened last year when I was living in the beautiful city of Bath. I'd never actually used public transportation on a regular basis, and I'm pretty sure I'd never been on a real bus in my life, so my initial experience was rife with insecurity and cultural faux pas. Learning the ins and outs of a transportation system is one thing, but learning them in another country in another monster altogether. I got used to it quickly enough, since you can pretty much walk across the entire city in half an hour. There weren't many bumps, aside from one time when I accidentally took the wrong bus after seeing this bizarre amateur play about Elizabeth I and ended up alone in the middle of the residential part of the city in the dead of night. That was fun.
So one time I was sitting on the bus, minding my own business, when an elderly Italian man got on and started speaking very loudly to nobody in general. He sat next to me and started talking about life and being in England and so on. It was amazing. He was just so loud and so Italian, and when he actually said "MAMMA MIA!" I almost choked. It was like listening to a caricature. He proclaimed to the bus at large that he liked me (I'd barely said anything to him), and I almost had another fit because you could just feel the discomfort of those poor English people who were trying SO HARD to ignore the loud Italian man. Oh, it was precious.
Anyways. Probably not as exciting as taking the subway on a daily basis, but...hnng, I love the world.