Who Let The Child In?

My sister and I were helping my mother cook for some of her guests that were coming over for dinner.
Of course, it was only the three of us in the house.
Her guests arrived at around 8:00 pm. It was sort of late, and we were all tired. We finished eating when my sister yells "Hey! COME BACK HERE." We looked around, and everyone was pretty much puzzled. My sister then ran over to the other dining table and started to crawl underneath it. We heard a child laughing. To me, it looked like she was trying to get someone out of there. Then, she stood up and asked our guests if they could ask their child to stop running around the house. To our surprise, they said they had no child with them. We thought they were joking, but they had this "scared" look on their face and so did we. My sister claimed there was a little boy running around, but our guests denied having a little boy with them.

When it was time for them to leave, we finally believed that they did indeed come without any children because they ended up leaving without any children at all.

That night, we all slept in my mom's room, scared to death. We still live in the same house today and we had experienced more paranormal action, but we think nothing of it.