Fortunately, I’ve never encountered a frotteur. But I have travelled by public transport all my life, and have been sexually harrassed three times. It’s amazing how dirty it made ME feel, at the time, for a day or so, while the fault was the guys.
Once, I noticed by his heavy breathing and from the movement I saw from the corner of my eye, that a guy (business type, trenchcoat) was jerking off in the seat behind me. I just moved to another seat further away.
Two months ago, a guy in the seat across from me the path started fondling himself through his jeans. I guess part of the exitement for him was that in the full carriage I was the only one in a position to see him, unless somebody would come walking through. Again, I got up without looking at him ( I didn’t want to give him that satisfaction) and sat somewhere else. I did call my BF on my cellphone to come get me from the trainstation, to be on the safe side, though.
Bah, I still feel annoyed thinking about it, and wish I could have made the guy as uncomfortable as he made me. But I can’t think of anything. He’d jsut have sat up quicly and denied it.
One last story: when I was 13, I boarded an empty bus, waiting for departure at the bustation. I sat down on my favourite seat, in the back, next to the window. A 20-something guy, boarded the bus shortly after me and sat next to me, snuggling up to me.
I must have been incredible naive, but it never occurred to me he was after me sexually. Being a polite girl, I made some conversation with him about the school book I was reading (It was about classical Greece). He seemed interested in the subject, but kept snuggling closer and closer to me, untill he had me pinned in the corner. Then it dawned on me: of course, this guy wasn’t being friendly! The bastard *was after my seat! * He wanted the back-bench all to himself!
I closed my book, looked at him indignantly and said “Okay, you can sit here if you want.” Quickly, I rose, wriggeled past him and walked briskly to the front seat, where I sat down and resumed reading my book on Classical Greece.
A few minutes later, the guy rushed out the bus without looking at me. In hindsight, I think he was a pedophile of some sort, and my response had flabbergasted him so he didn’t know how to act - much like a lioncub doesn’t know what to do with a gazelle that won’t run away.
Ever since, I still think the unexpected, unafraid response will puzzle and distract these guys more then anything else. In your case, if I had had time to collect my wits, I might have said, in a loud voice, something like: “Sir, you’re rubbing up to me. Please, I’d like to know why. And what, exactly, do you mean with “You cunt, I’m going to get you?””
But then again, I’ve travelled by public transport for thirty years, and these three experiences don’t weigh against countless peaceful travels and dozens of pleasant friendly or amusing encounters. 
Rock on!
but I blame my boss. I’m at work, on a different pc than usual and the guy just won’t leave me alone to get back to my Dope! 
