A silly word/acronym that teenagers concocted around the era of Green Day's album American Idiot. Many will claim this word is older, but most of them were either young teens when American Idiot debuted, or they're young teens now who are more familiar with 21st Century Breakdown. They tend who exhibit behavior that suggests they merely wish to aggrandize their level of dedication to the band as fans and their credibility as such.
The word is actually quite new, and it is also indicative of the attitudes of people who are peculiar enough to proudly say they have this fictitious disorder. In short, they're very young, they're "new" as fans and they therefore care too much about proving that they are fans, they wish they had tenure so they substitute it with obsessive, fanatical stances, and most of them will move on to the next popular and/or revitalized band as they age and follow the changing trends.