Micky (Fallout 3)

Micky is a vagrant outside Megaton who repeatedly asks the Player Character for Purified Water. Every donation of water gives good karma to the PC and appears to be a unlimitedly repeatable action, thus providing a karma-farming opportunity especially if the player has a home in Megaton and thereby unlimited water. If you murder Micky without believing anybody saw you, the residents of Megaton will still become aggresive, possibley due to Stockholm, although he fails to shoot at you even after Micky's death untill you enter Megaton