Told first person today. I did it in a kind of sneaky way, though. I wanted to see if he would hate me for it. Luckily, it turned out fine.
Me: I have a test for you. A test to see how well you accept what other people like. Are you ready?
Friend: Sure.
Me: Remember, this is only a test.
Friend: Ok.
Me: I am a brony.
Friend: So?
Me: Good job, you passed!
Friend: Ok?
Me: Remember, I never said this was true.
Friend: I know.
Me: Can you keep a secret?
Friend: Of course.
Me (whispering): Its true.
Friend: Really?
Me: Yes. (My voice was kind of shaky at this point)
Friend: Ok.
Silence
Friend: So are you really a brony?
Me: Yeah. By the way, thanks for not hating.
Friend: It's fine. I won't be a brony though.
Me: I never asked you to be. Thankfully I didn't have to try to explain.
Topic then changed to games.
This is all after he said he would kinda hate me if I was a brony. Thankfully, I realised that if he wouldn't accept it, he isn't a good friend anyways.
Sorry for the long post. I even left some minor parts out where we joked about it. If anyone wants to help me out with this forum, thanks, as this is my first post and I know absolutely nothing.
Edit:
I finally have a worst one.
I told a kid on my bus who I thought was a good friend, not sure anymore, that I had been dared to watch every episode of MLP by someone (this is true, the person who dared me didn't know and absolutely hates bronies) and said I don't want to watch every episode again. He then asked me who the rainbow pony was and I said "the one with rainbow hair?" but he meant a completely rainbow pony. He then screamed that he likes rainbow ponies for no reason and another anti-brony was in the seat in front of us. Now this kid keeps telling me I'll get r*ped by ponies while I'm sleeping.