Doing absolutely nothing while something very bad happens. It refers to the 1964 rape and murder of a woman named Kitty Genovese in Queens New York. Several dozen of her neighbors heard for help and none of them did anything to help her. It has oftent been applied to the Rwandan massacres in the mid 1990s, and the massacres currently occuring (January of 2005) in Darfour Sudan.
See also Hot Girl Effect.
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