let's say in subway once there're plenty of ppl or in the bus?
like it's kinda unintentionally, but u know it's not 
BTW: any reason you ask this?
Otherwise, if you are certain they are doing it on purpose repeatedly, there is nothing prohibiting you from saying, "please do not touch me again." Say it loud enough so that they can hear you, and so people around you can also hear you. Don't put up with that. Women are not things to be gawked at and touched and made to feel uncomfortable for a stranger's pleasure.
IRL I'm a very polite girl, but in this case I would never use the word 'please'. You're not asking a favour, and you don't want to give the perv the idea that you're submissive or feeling uncomfortable. Just a 'Don't touch me!' straight to his face would be better.
Plus any gentleman near would then keep an eye on the situation.. I would, and if Mr perv decides to get squirrely just lock him up in a full nelson and let miss lady have at him 
It is very nice to know there are still real gentlemen out there! Unfortunately many people are just unaware something is brooding.
I had this when I was about 12 yo. I was with a friend (girl) in a library and a group of 12-14 boys our age were starting to harrass us. Touching us, talking dirty. We told them to stop, but they did not listen. We starting running, first to the nearest adult who did nothing, later all through the 8 floors to the congierge/security guard. You would say a group of running, screaming, hitting, kicking, biting kids in a library would draw some attention. But NOBODY noticed anything wrong! Not when my friend started crying almost hysterically. Not even when one of the boys had a clearly broken nose with blood all over his shirt (my doing
).
We fled the library, crossed a busy market and went into a subway station. Still nobody seemed to notice or care. Untill we met a few elderly men on the other side of the platform. They stood up for us and one of them hit one of the boys with his walking cane. The man really had to whack around to keep the boys off, but he managed. These grandpa's rode along with us on the subway to our destination, so we would feel a bit more secure. I am still very greatfull to them!
When I'm in a subway or bus and I have a feeling something similar is about to happen, I just go over and sit or stand next to them or nearby and make eye contact with both the girl (for support) and the perv. Usually that's enough to make the perv stop. If not, I will step in. Had a few times that when the perv left, the girl whispered a thank you to me, because someone did notice and care.
