Is this a ghost?

My little sisters share a room and this morning my littlest sister woke up around six am and she came into my room and asked if she could sleep with me. She was crying a little so I asked her what was wrong. She told me a man that looked like jack from the Christmas story was rubbing his knees on her bed. Then she went to sleep in my room and went downstairs a few hours later, not talking to my other sister at all. Then my older sister came into my room and told me something was moving on ryanns bed. ( Ryann is my little sister) I found it kind of odd. Then tonight they both came in my room and told me that he was back. I asked who? And they took me into their room. They said he only shows up when the lights are out. They shut out the lights and said he was sitting there beside the closet door. They turned on the lights again and I told them he wasn't real and they were just imagining him. They shut out the lights and they both panicked and said "KYLEE! HES COMING TO YOU" and they turned on the lights again. I never saw anything this whole time. They would turn the lights on and off and keep seeing him in the dark. I told them to tell God to protect the house and that he would disapear and they prayed, shut out the lights, and said at the same time " he's gone!" So I don't think they were lying. I'm just wondering what kind of ghost is skinny and resembles jack from the nightmare before Christmas, rubs his knees on your bed, and is only seen in the dark.