The "Bloody Mary" game, which involves staring into a mirror in a dimly lit room, has been popular for decades. While its origins are unclear, some believe it dates back to a Robert Burns poem from the 18th century and others point to a 2010 experiment by an Italian researcher named Giovanni Caputo.
A research experiment in Italy in 2010 showed that out of 50 test subjects who stared at their faces in a mirror for 10 minutes in a dimly lit room, 66% reported seeing deformations of their face, while others reported seeing the face of a parent, animal, or old woman.
Researchers explain the neuroscience behind the "Bloody Mary" legend, suggesting that it's our brain's tendency to fill gaps that creates monstrous images in our mind's eye.
Mental Floss has linked the "Bloody Mary" game to a Robert Burns poem called "Halloween" from 1786, where party ideas were suggested for Halloween in the 18th century. They suggest that the word "Mary" got twisted over the years and this is where the game came from.