Don't see any reason to hide it or be ashamed of it. If the topic warrants me mentioning it, I will. If not, I don't randomly shout it as passersby, either. Most of my friends know, and I even found out that some of my friends who I thought didn't even know what it was actually played as well when I mentioned it in passing. Like above though, I usually just say that I write stories collaboratively on a forum if I'm not sure the person in question understands what roleplaying means. That's because most of the time when I mention roleplaying, people take it to mean either tabletop roleplays or RPG-genre games (which I also play, but yeah), so it's easier to avoid confusion.