A lot of times, the person is "sexually aggressive" and is sexually attracted to you. They also may think you are the same way, which is why they dont stop until you tell them to. Make sure you are very firm in your resistance to their behavior, (or if you like it, that is your business) and if you want them to stop, threaten to tell someone of their actions, and they will often back off. Keep in mind that it is illegal though! So you can threaten to tell someone in high authority.
