It's probably nothing...

As the train chugs along, you feel something rest on the outside of your skirt, just on your rear. Instinctively, you hit it away, just realizing it was someone's hand. The hand rests itself on your rear once more, and starts to try to reach under the skirt.

You hit it away again, but it only comes back, more aggressively. The hand slides up the back of your skirt, gently rubbing your ass beneath your panties.

Meanwhile, another hand caresses your thigh, pushing its way up your leg. Whenever you bat the hands away, they just keep coming back! What should you do?