10. When people don't understand what you're talking about :(
Since I'm a Harry Potter fan, I (like so many others) talk about my fandom. Loads. I talk about it constantly. When I'm talking to my friends, I could say something like, What house are you in? or, Why do you act so much like a Muggle?
I then of course, have to explain it, which gets boring after awhile. And when I talk about Percy Jackson, I have to explain that too. If I talk about The Hunger Games, I've got to explain. I actually told someone that I took a test (actually three) and the first one's results were: I would have survived The Battle of Hogwarts. Second one: I would have won The Hunger Games. And third: If I were a HP spell, I would be Avada Kedavera (which by the way means: I will DESTROY as I speak. And Abracadabera means: I will CREATE as I speak. So J.K. Rowling did a play on words. You go, J.K.!) I then had to explain it to one of my friends (because the others have already learned by now.) So if you hve a friend that is into a fandom, you better do some research, or even read the books. Or even watch the movies. Or do both. All that matters is that you have the tiniest bit of knowledge on what they're saying. Trust me, they'll be glad you made so much effort on trying to understand them better. But it's best if you read the books, they give you more knowledge than the movies, because THE MOVIES LEAVE OUT ALL OF THE IMPORTANT THINGS IN THE BOOK.
Once again, I hope I didn't offend anyone.