This urban legend involves a teenage girl who was home with her little sister while their parents were out on the town. After watching some television together, she sent her little sister to bed and then went back downstairs to watch more TV. Eventually, she got bored with what she was watching and turned it off, then curled up in a blanket on the couch and watched the snow fall through the large sliding-glass window in the living room. She had only been watching for a few minutes when she saw a man walking toward the sliding glass doors with deadly purpose. He started to pull something shiny out of his coat and she dove under her blanket in terror.
After a while, she pulled down the blanket and found that the man was gone. She called the police, who immediately rushed over to the scene to investigate. Upon examining the premises, one of the first things they noticed was that there were no footprints in the snow. And with the rate of snowfall, there was no way they could have been covered that quickly. Puzzled, the officers inspected the residence and noticed wet footprints on the carpet leading straight up to the couch where the girl had been sitting. The madman had been behind her the whole time and what she had seen had been his reflection in the window.
Source: http://listverse.com/2014/07/30/10-bone-chilling-urban-legends/