I'm not fully a closet brony, I tell those who, I guess, will find out anyway. So far, that's only five people. Four people who I've been to anime conventions with (including my older brother who, sadly isn't a brony) since there was pony stuff, and I bought badges and fanart. One other friend knows simply because we were discussing fandoms on MSN and she asked if I knew anything about all the MLP stuff everywhere. I came out and told her I watched the show and after an awkward conversation, it was fine.
I won't announce my bronydom to others in my school because I've gone through my entire school life being bullied. I've finally reached the point where people have nothing new to mess with me about and have to bring up stuff from a few years ago instead, which doesn't bother me as much, so telling people I like My Little Pony won't help that.
I will try telling my best friend, but she really really hates it when I talk about fandoms. Really. (I know, I know, "why is she your friend if she hates something so special to you?". Well, she's been my best friend for 11 years now. And I don't like 'breaking up' with friends) I also wanna tell my parents because I will be making a "fandom wall" in my room at some point covered with posters and pictures of my different fandoms, and I have pony stuff I want to use for it.