It's insulting to refer to someone as a creep.
Mary is sitting at a bus stop waiting for her bus when a stranger walks up and starts talking to her.
Mary wants to be left alone.
Mary politely excuses herself from the conversation, letting the person know that she is uncomfortable talking with strangers.
Mary calls the stranger a creep and tells him to get away from her.
The person stops talking to Mary, and she feels as though she did the appropriate thing given the situation she was in.
The person's feelings are visibly hurt and Mary begins to feel badly about how harshly she spoke to them.