Legend has it that if you say "Bloody Mary" three times into a mirror, then Queen Mary Stuart will attack you. Personally, I prefer the South Park version of the story, starring the ghost of Biggie Smalls.
Playing up on the legend of Bloody Mary and poking fun at its rival, McDonald's, a Burger King outlet in Sweden has created a haunted bathroom. If you say "Cancelled Clown" -- a reference to Ronald McDonald -- three times, then the clown will appear before you. Business Insider reports:
The software, installed by a Swedish agency named INGO Stockholm, is trained to listen for the phrase "canceled clown." If it hears it three times, it dims the lights, makes a noise, and plays visual effects on a screen behind the two-way "smart mirror."
Ronald McDonald has been "cancelled" in that McDonald's has gradually removed the mascot from its advertising.
-via Dave Barry