I've been listening to a paranormal podcast recently and often when they mention an incident that involves strange noises around a house, one of the hosts will say: "maybe there's someone living in the walls?!"
My question is: is this just a silly joke, or does the average American home have enough space inside the walls for a person to hide in? I'm from the UK and someone would have to be about two inches across at their widest point to live in the walls of any house I've ever lived in.