We discovered the urban legend of a curse called the Grim Mugger. If you say "Mug to the end" 3 times in front of a mirror, you will suddenly be consumed by a desire to mug furiously. However, you will die of exhaustion from the rate of your mugging 13 minutes after you say it.
Attack.
Mugging.
Death.
The cause? You have summoned the spirit of a dead mugger who died from sleep deprivation, starvation, and dehydration after mugging for days non-stop. Her spirit is vengeful as she never got to take the exams, so she walks the earth, letting other muggers gain tremendous mugging skills before they die like her.
(The above pictures were taken with a special high speed camera for capturing ghosts on film.)