A guy was jogging down the street past a psychiatric hospital. There was some construction going on with a big, temporary plywood wall placed between the sidewalk and the hospital grounds.
As he jogged by, he heard a large group of people on the other side of the fence excitedly chanting, "13! 13! 13!" over and over.
Curious, the guy slowed to a walk and tried to find a way to see over, under or around the fence to see what the hell was going on on the other side and why all these people were yelling, "13! 13! 13!"
Finally, he noticed a small knothole about 3 feet off the ground. He got down on his knees and put his eye up to the knothole to try to see through it.
As soon as he did, a long stick came through the hole and poked him right in the eye.
He jumped back grabbing his eye and, on the other side of the fence, heard the chant, "14! 14! 14!"