BLOODY MARY!!
Urban Legend: Chanting "Bloody Mary!" thirteen times in front of a candlelit mirror in an otherwise dark room will summon her vengeful spirit.
The Story: Go into a room with a mirror and turn all the lights off. Bathrooms seem to be perfect for this since they almost always have a mirror and are usually dark at night with the lights off and the door closed. Light a candle, look into the mirror, start chanting "Bloody Mary" . You have to do this  13 times, of course. You should see Bloody Mary behind your left shoulder after the thirteenth time.
Beware, she has been reported to 1.) Kill the person calling her, 2.) Scratch their eyes out, 3.) Drive the person mad or 4.) pull the person into the mirror with her. This is an old legend, it has been around for ages. A folklorist,  Janet Langlois, published an essay on the legend back in 1978. At that time, the legend was wide spread across the USA and a popular slumber party ritual done by girls as well as boys.  No one knows the true origins of the Bloody Mary tale, she's been known to be anything from a witch that was killed for practicing witchcraft to a modern day woman killed in a car crash, depending on what part of the country you live in. It was made popular again in the film Urban Legends in 1999.