Yes I am a huge gamer, but for the most part I don't talk about it when out and about. Generally, if there are girls there (chicks for you brah-skis) I won't really talk about games. Probably because most girls show no interest in them. I wouldn't say I'm embarrassed about it but I definately don't bring it up in conversation.
Also a lot of people I hang out with are NOT gamers, so why would I start talking about things that they have no interest in. I know some of them game somewhat but only really play the big games out there (Call of Duty, Halo, Madden/Random EA sports title, etc...) and even then I only talk about them a little bit.
I'm not sure why this is, I've definately noticed it tho. My best friends know I'm probably the biggest gamer out there, but if you ask people I hang out with from sports and such I never really talk about it.
Case in point: I was at work talking to a co-worker about Call of Duty, so I was like ok he's a gamer. So I said I like to play RPGs and he said "what's that?" Haha, so my only conversation with him about games is pretty much Call of Duty or Madden.