Maggots

Maggot is the term that is given by American metal band Slipknot to it's fanbase, approximately 3,000,000 people at last count. Maggotism is not to be confused with emoism as Slipknot is a heavy metal but not (always) a death metal band. It remains safely in the goth territory, not in the "not-sitting-on-the-knife-edge-but-using-it-to-slit-our-wrists" teritory.

Origins
This one's easy.
 * 1999
 * Slipknot's lead singer, Corey Taylor and bassist Paul Gray
 * At a Slipknot Conecrt in northern America.

Simple as.