Hmm... Well, the revenge is different depending on the type of person.
If it were a vegetarian I already know exactly what I'd do. I'd kidnap them and lock them in a room with nothing but a table and a bucket in it. On that table would be a large 12 lb cooked steak. They are not allowed to leave until the entire steak is gone. Now of course I'd have a camera watch them, give them the water needed to live, and even replace their toilet (the bucket) when they sleep, but in the end it only matters how stubborn they are.
If they are really stubborn, the steak gets gross and cold, then they die. I didn't personally kill them, it was all them. Otherwise whenever they crack and eat it I'd let them go and they will never be the same again.
As for anyone else, I'd just kidnap them and remove their vocal chords before letting them go. I wouldn't leave any trace of me though :P