People who damage other people's property for a thrill.
My best friend has MS, and is on a fixed income. She has put a lot of effort into making the small yard in front of her apartment pretty; she bought some large planters and planted flowers in them. Sometime late Saturday night or in the wee hours of Sunday morning, someone one rolled one of the planters down the hill by her apartment and it shattered.
Even though I am sure who ever did it did not know her personally, it makes me so mad, she is such a giving person and does so much to help others; it hurts that someone would do something so mean to her.