Fans of Prince Poppycock (John Quale), who is an opera singer that appeared on Americas Got Talent in Summer 2010.
Poppies tend to be fans of opera music (or were converted after seeing the Prince perform). They usually will have their profile pictures/avatars as pictures of the Prince or images of a poppy flower. They also tend to mimic the Prince, by giving themselves silly nicknames, like The Grand Duchess Lillypop and talk very elegantly, like, What a quaint day I have had to day, my fellow poppies!
This term is used by The Prince to describe his fans, the fans themselves, and those familar with Americas Got Talent.
* These videos are coming directly from Youtube, they may or may not be most relevant to the word "Poppies"