This.
Nobody knows that I am a brony except for other bronies, pegasisters, and my friends on the Internet, and I plan to keep it that way for a while until I get comfortable about telling them.
It's really not a big deal, but I can easily tell that both of my parents wouldn't be very supportive.
I'm not very good when it comes to explaining things either, so when I tell them that I like My Little Pony, they'll instantly think of G1 or G2, considering that I live with my grandparents who are very serious. Even if I tell them that this generation is different, they'd still think strangely of me.
I would definitely have some way to make it sound worse, whether I would mean to or not.
I can imagine that once I tell them, they'll be like, "Son, is this your way of telling us that you are gay?"
I don't know if it's just me being paranoid, but I just think it would be too embarrassing to tell them that I like MLP.