Do you shove it in everyone's faces by wearing DBZ shirts and amazing everyone with random bits of trivia relating to the series?
Or if someone asks whether you like it or not, do you keep it cool and simply say, "yes"?
Personally, I actually kept it as a secret for a bit after a friend told me "Dragon Ball Z's gay" back in year 5.
About two years later, I began to drop hints either by playing the games with my friends or showing them episodes of Abridged and Alternate Reality Dragon Ball Z. After that, I actually tried to get my close friends into the series by watching it with them and I was more open about it with some of my nerdier mates, in fact, one of them was sort of a casual fan for a while. This is basically how it is now, and I do talk about the series frequently with one of my other friends since he's into superheroes, etc. I don't make any sort of effort to hide it, like I did when I was 9, it just seems silly, but I don't really go all in either because there's still that stigma surrounding it- that it's just another show like Pokemon and Yugioh. There is one friend who I won't share my interest with since he tends to be a bit ignorant and I can't be bothered arguing with him (he tends to dismiss everything he's not interested in). Speaking of arguing though, a guy who I know is heavily into the series (he owns all of the orange bricks) was making fun of Masako Nozawa's Goku during class one time and I was tempted to start a discussion with him, but I instead continued with my "low-key" act. It's funny, I really like to go out there and defend Nozawa's Goku whenever someone mocks it on the internet, because it kind of annoys me, but for some reason I wasn't really annoyed when someone criticized it in person. I guess it was because I could see that they were a fan of the show, they enjoyed it and it was something we had in common, regardless of the version. Anyway, I have a hunch that a couple of my other friends are into the series, at least casually, so I may have to follow up on that.
Random Story: Last year, I started catching on to the fact that there were a lot of people at school who were aware of the series and even fairly big fans of it too. (I've actually heard a lot of DB-related discussions during my classes, mostly maths.
) Someone asked me and a couple of others on whether we'd seen Dragon Ball. I tried to keep it cool, but my cheeks ended up giving me away. 
