Now don't get me wrong, I have no grudges against any Mormons, but after getting bombarded at my old house for weeks on end by their door-knockers (and pretending I wasn't home) I decided to exact my revenge...
I drove home one night after work and saw a pair of Mormons walking my neighborhood (again) and pounding on doors. So I whipped up a batch of my famous fake-blood from my Drama days, grabbed a large cleaver from the drawer & lit candles all over the house. Grabbed an apron, smeared my fake blood all over it and the cleaver and waited.
Sure enough, the door knock came about 10 minutes later...I got up & answered the door carrying the knife. Well they just gaped...stammered a bit, and one finally sputtered out their preset "Hi, we'd like to tell you about the Church of Jesus Christ of Latter Day Saints." I looked the guy right in the eye and told him flat out "Sorry, but I worship Satan. If you'd like though, I'm in the middle of a ritual and I can show you all about MY religion."
Well, they ran like h*** as fast as they could and I've never had a knock on my door by them since. Its a shame I had to lie that badly to get rid of them, but I don't feel the slightest regret.