Are you out at work?

I am freshly out of the closet but I am definitely not shouting it from the rooftops yet. I just started a new job today and my coworker started talking to me about women. I just nodded and didn't really say much but it just reminded me of how much I hate having to pretend to be someone else. I would have love to have said, "Actually I don't care to check out that girl's butt because I'm gay."

What do you guys do in these situations? I can't be fired because I'm gay, I know that. I work at a university with other students who hopefully are open minded but I guess I could still face discrimination.