There’s no shortage of How I Met Your Mother fan theories circulating around the Internet. The CBS show ran for nine seasons, and left viewers with plenty of hidden nuggets and unresolved story lines to keep them guessing for years. Without concrete answers, devoted fans had no choice but to cook up their own philosophies regarding the show and its characters. If you watched all 208 episodes, it’s a safe bet you can answer your fair share of plain old How I Met Your Mother trivia, but these are the fan theories about How I Met Your Mother that might just blow your mind - not to mention change the way you see certain scenes, episodes, and characters. Which ones do you believe? Vote up the best HIMYM fan theories. And when you're done with that, you can also check out other shows like How I Met Your Mother to obsess over, and form your own theories!