It's not hard to gain Good Karma in Fallout 3, actions that award positive karma are all around you, and offer significant boosts to your karma level. Providing water to beggars outside of Megaton, Rivet City and Tenpenny Tower is an easy, repeatable way to gain Good Karma. However, without killing a named character, or searching extensively for an unnamed/respawning travelling merchant to kill, what are the easiest and most repeatable ways to acquire Bad Karma?
I know I can activate an owned computer repeatedly to lower my karma, but this is time consuming, and does not lower my karma at the same rate as donating Purified Water would increase positive karma.
In terms of equivalents, what is the easiest, most repeatable action to be an evil character?