1. Juggalos

2. The Sect of Gadget Hackwrench

3. Tosh 5.29

4. Jediism

5. Dudeism

6. Plushophiles

7. Teen Werewolves
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They're not goth or emo. They're werewolves! Okay, mom!
8. Model Fight Clubs

9. World Of Warcraft Fan Conventions (Blizzcon)
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BlizzCon is a convention all about Warcraft, Starcraft, and Diablo. Video game fans spend days in a convention center in Anaheim, California playing video games, going to panels, and participating in Q & A sessions (see Red Shirt Guy video for reference).
10. Real Life Quidditch Players
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The idea of Quidditch was first conceived of by J.K. Rowling and written about in the Harry Potter book series. Super Harry Potter fans turned the fictional game into the real deal! No, they don't fly on broomsticks, but they play the game almost exactly as it is written in the books. Many colleges in the U.S. are starting Quidditch teams, and fans are wishing to legitimize the sport.