You know that you're and A.T. fan when you: Dress up as Finn or any other A.T. character for Halloween.
When you: know all the words to every song.
When you: sing the theme song every time the show comes on.
When you: yell, "Adventure Time!" when someone asks you what time it is.
When you: go out and buy a dog just so you can name him Jake.
When you: rant on and on about A.T. to anyone who will listen.
When you: practically pee your pants when you find new A.T. merchandise for your collection.
When you: acually have an A.T. collection.
When you: swear on Finn and Jake like you're swearing on your life.
When you: treat non-A.T. fans like they have the plague.
When you: beat up some random guy because he looked like the Ice King.
When you: have so many A.T. action figures and plushies that they amount to a whole Land of Ooo.
When you: save your allowence just so you can get the monthly A.T. comic book issues.
When you: own all the complete seasons.
When you: watch one episode every morning because it helps you start your day.
When you: absolutly refuse to do anything if your parents won't let you watch the episode to start your day.
When you: force your parents to put an A.T. decal on the car.
When you: can't even see your bedroom walls anymore because it's been invaded by A.T. posters.
When you: almost go into cardiac arrest because you missed an episode.
When you: think, "Wait, that last one doesn't count because I, like, NEVER miss an episode".
When you: have a computer that's flooded with A.T. pics, vids, and wallpapers.
When you: refure to Pen Ward as "Creator of all things Holy".
When you: try to do a fist dump with Finn and Jake through the TV screen only to realize that it won't work.
When you: die a little bit inside when you think of A.T. coming to an end one day.
When you: learned Korean so you could understand Lady Rainicorn.
When you: nearly cried when you heard that LR was pregnant.
When you: know all the names of the princesses and how many there are.
When you: qoute A.T. constantly.
When you: sing the songs constantly.
When you: have a Finn/Fionna hat.
When you: wear your A.T. shirt so much that it's literally falling apart at the seems.
And lastly: when you're a true Adventure Time fan... you know.