McKamey Manor in Summertown, Tennessee might be the scariest haunted house in the world, according to UPI. The completion prize is $20,000, but no one has ever finished. To even participate, visitors must sign a 40-page waiver, have a drug test and a physical and have medical insurance. They must also watch And Then There Were None, a two-hour film which displays past contestants who all agree: "You really don't want to do this." Every contestant is videotaped to prove that nothing illegal happened. McKamey says the key is a "mind game" that uses hypnotism so visitors trick their own minds.