The Legend of "Bloody Mary"
Historically, the "Bloody Mary" ritual encouraged young women to walk up a flight of stairs... backwards... in a darkened house... while holding a candle and a hand mirror. (Because everything about that is safe.) As they gazed into the mirror, they were to say the name "Bloody Mary" three times... which would let them see their future husband's face. There was, however, a chance that they would see a skull (or the Grim Reaper), which indicated they were going to die before they married.
In the present day, the summoning ritual requires that the lead participant must not look directly for Bloody Mary, but at their own image in the mirror.
Variations of the incantation ritual involves: the number of times Bloody Mary's name is called; spinning around after every time you say her name; or taunting the ghost by saying, "I've got your baby." Taunting Bloody Mary about her baby indicates the ghost has a connection to England's Queen Mary I, also known as "Bloody Mary", whose life was marked by several miscarriages. (Personally, if you're making fun of someone for losing a baby, I hope a ghost DOES appear and eats your face.)
Allegedly, Bloody Mary appears as a corpse, a witch, or a ghost; sometimes she is covered in blood (hence her name). The folklore surrounding the ritual states that participants may endure the ghost screaming at them, cursing them, strangling them, stealing their body or soul, or drinking their blood. (Soooo... all positive things.)
This does beg the question... WHY WOULD YOU RISK THIS HAPPENING?!!! Be my guest. try it out. Taunt a ghost. That ALWAYS ends well...