Wikipedia describes it as a thought experiment in ethics that goes something like this:
There's a runaway trolley barreling down the tracks. Ahead on the tracks there are five people tied up and unable to move. The trolley is headed straight for them. You are standing some distance off in the train yard, next to a lever. If you pull this lever, the trolley will switch to a different set of tracks. However, you notice that there is one person on the side track. You have two options: (1) Do nothing, and the trolley kills the five people on the main track. (2) Pull the lever, diverting the trolley onto the side track where it will kill one person. Which is the correct choice?
There are all kinds of variations to extend the problem, including throwing large people off bridges to stop the train. It makes for an interesting and often surprising discussion, the kind where your spouse isn't sure she wants to ride in the same car with you anymore.
Recently in McSweeney’s, Kyle York wrote a brilliant, laugh-out-loud send-up of the trolley problem. I don’t know Kyle, but I now consider him my inspiration for the following variations, designed to test your meddle as a modern entrepreneur.