I've never been attacked (verbally or otherwise) on public transit, but there was this one time in New York City when, as I was emerging from a subway station on Lexington Avenue, my cell phone went off. I was using the TOS communicator noise as a ringtone. Lots of people heard it and started laughing at me. I was rather embarrassed by that.
I would have liked to have that ringtone on my flip phone years ago, but nowadays I let my Nerd flag fly by still using the Buffy the Vampire Slayer theme song as my ring tone.