I can't believe the number of posters on here who said they would cut the cord (I assume AFTER they had unplugged it
). I think that by cutting the cord you take a minor problem (someone stealing your electricity) and possibly turn it into a MAJOR WAR. This person is your neighbor. Someone you might be living next to for many years. Do you really want to start an ongoing war with a close neighbor over a few cents worth of electricity?
My personal opinion is, anyone bold enough to steal someone else's electricity can probably figure out a way to get even with you several times over for cutting his cord. Just look at Scroll's post for a few ideas on how this person will get even with you.