How does the bloody Mary chant work like what do you do and say?

There are a few different versions, but these are the two most common ones. In both, you stand in a room (usually a bathroom) with the lights off. You spin around three times with your eyes closed while saying the chant, then turn the lights on. Different things are said to happen, ranging from the faint appearance of a scar on your neck to the untimely death of the chanter.

One version of the chant is simply "Bloody Mary, Bloody Mary, Bloody Mary."

Another is "Bloody Mary took an axe and gave her father forty whacks. When she saw what she had done, she gave her mother forty-one." Despite the fact that this stemmed from Lizzie Borden, not Bloody Mary, at some point the two merged for this activity.