Why is The Sledgehammer in the Cabinet?

The guys at my work, my boss and the guys doing the construction have this running thing with a sledgehammer, they will hide it in each others beds and in coats and in all sorts of places, When I got a phone call this morning from my boss saying to hide the sledge somewhere I placed it in the cabinet... then was told by the head of the construction guys that I better not hide it where I had been told to... so I give you: