The first strange experience I had was during my sisters' tenth or eleventh birthday party. At the time, my family lived in a house in a blue-collar town in New Jersey.
The house was set up where the front door was up a flight of stairs. Once inside, there was a landing that lead to another flight of stairs upstairs and another leading to the lower level. Downstairs, there was a long hallway with a doorway leading to the garage. At the foot of the stairs, which formed one end of a long hallway, there was a closet under the stairs. There was a laundry room, at the end of the hallway, and finally large living room.
My sister had invited all of her friends, and everyone was having a good time. After eating cake, the grown-ups went upstairs for coffee and the kids stayed downstairs to play on their own. At a certain point, we all decided to scare each other by telling ghost stories in front of the laundry room.
My sister and I had always thought of it as the creepiest spot in the house and it proved to be the perfect spot to tell ghost stories. When you opened the laundry room door, you stared down a long dark room with a shaded window at the end. The doorway to the laundry room was a small recess at the end of the hallway.
The house quieted down as we started talking about scary things. After a few of these stories, everyone started to get into the spirit.
My sister and I were sitting at the end of the hall looking down its length. From our vantage point, we could see the wall along which the door leading to the garage was. We were midway into someone's ghost story when my sister suddenly noticed that the door leading to the garage had suddenly popped open just a bit. She remembered that the door was definitely locked.
We walked over and closed the door and made sure to lock it again.
By then, all of us were terrified and thoroughly petrified in our little recess. As little kids, not one of us wanted to move out of our spot or make a noise.
Just then, someone rang the doorbell which made everyone jump three feet, but was enough to kill the moment. Everyone started laughing.
Our house was new, when we bought it, and nothing strange had ever happened to anyone in my family there. Now that we're older. My sister and I still bring up this incident with my sister and we both have a good laugh. She still swears that she locked the door. Its not a big incident, but definitely something that we couldn't explain.