You can give them all a mirror while you say the story. (Or not!)
To SCARE them Silly!
Whoever is foolish enough to say Bloody Mary three times in the mirror is sure to die. Once upon a time, there was a woman called Mary Worth. Everyone insisted she was a witch, and no one dared go newar her house. One day, all the girls in the neighboorhood went missing one by one. No one knew where they went. The bravest of the towns-people went to old Mary’s home. Strangely, she looked younger and more up to date than before. Seeing they had no proof, they left. Then one night, an old woman tried to stop her daughter from going outside. The daughter kept walking, and no matter what, they could not stop the little girl. Finally, they discovered that she was walking to Mary’s home. Mary killed the girl, and drank her blood to make her younger again. The woman screamed, and her husband ran to her with a pitchfork. Burning Mary alive, she told a curse that whoever says her name 3 times in the mirror at the minute of midnight will get the same treatment she did on that very night and live as another Bloody Mary forever.