well, if you ask me Tattoo would be too much. tattoo's are permanent. who guarantees that you'll like mlp in 20 years? I mean, it's simply too much. I mean, you can express yourself trough other things like clothes or something that means much for you (like car sticker or highback sock (which I'm planning to get)) but tattoo is too much. if you ever want to get tattoo on yourself it has to be something that you know you'll cherish for rest of your life (for example: ONLY tattoo that I would get ever in my life if ever I get to Olympic games to compete. it's kinda my life long dream to get to olympics and Slopestlye will now be in Sochi 2014. only then if I get to compete I'd get olympic circles, because I believe in peace and united world in sports and I know that i'll always feel this way towards olympics.)
Oh ho! Well, at least I'll have infamy somehow then. If you want a way of showing to the world you're a pony fan, how about shirts and pins? Or both! Stick pony pins all over your pony shirt.
I'll blast some pony tunes from my car with a pony paint job, get out with my pony shirt on, whistling previously mentioned pony tunes, walk into a pony shop and buy some pony gear, drive home to my pony painted house and watch some ponies on my ponified computer, while talking to my pony friends on my phone with the pony ringtone and wallpaper. But no pony tattoo. Besides, the fact that this is my bed should be enough. EDIT: IT'S G3 I KNOW. It was a joke by my parents. But you know, better than no ponies.
Well personally, if you feel that it's too much then don't do it. But when i turn 18, i'm getting AppleJacks cutie mark on my hip.