Rocks and water bottles

A couple of months ago my unit got a bright idea to string camo netting over the port-a-johns to keep them out of the direct sunlight making them a few degrees cooler inside.  It actually works.   Earlier today, I was doing my business in one of them and a prankster Marine noticed me going in there and started throwing rocks at the door to make me jump.  After all of the time I've had pranks