A sack wacker is a person who enjoys delivering fatal shots with a fling of their hand to the genital area. The aim of sack wacking is to make the person cringe with pain and vomit. When sack wacking it is important to laugh after u have just sack wacked or it will be uncounted. The best place to some one is preferably on the left testicle, this will cause most pain.
Colesy is the king of all sack wackers, he never misses.