I have discovered it and tested it on numerous subjects. Gone are the days of the typical 'Burn down your house and dirt block it' griefers now comes the rise of the String Theory! Each subject was driven to homicidal fury by this string theory and so I decided to share it with you all. Get a stack of string - Place all over the inside and outside of their house. It doesn't damage anything, or interfere and is barely visible at a reasonably close distance. But if you are walking around the little block highlights spam your screen and when you move/punch you get string in your hands. It's pretty funny and doesn't do any harm to the other person so it's not exactly griefing but the rage is usually disproportionate and amusing.