Passing Ghost

One day my sister, my boyfriend and I were watching a movie at my house, we have a small TV Room, that serves as a guest room when needed. It's a small space, with a Sofa bed, a good size TV and a small window. 

We were watching Shrek, and we closed the door, as my younger sister was sleeping on the next room, so we didn't want to wake her up. It was around 8:30 on a Sunday night. All three of us were watching the movie, when the door opened violently and there was no reason for these. We all remained in our seats looking towards the door, I then got up to close it, when I saw a white mas go through the door and inside the TV room, it was a white mass, very dense and the size of a grown human, it had no shape, it in height and dimensions it was like a human size. It went right across the room, right before our eyes and disappeared one it reached the small window opposite to the door. 

After a good 30 seconds of shock, we looked at each other. We all had a puzzled expression and ran to the window to look where the mass went. We saw nothing. We searched the house, but everything was in order. My sister was sleeping in peace in the room next to us. My parents were watching TV on their room. It was just an instant, it was just passing by. My sister, my boyfriend and I sat and discussed what we saw. We all saw the same thing, we described the same experience, but none of us had an explanation for this. 

We never experienced anything like this again. That's why we call it a Passing Ghost.