Usually on a dating site, so it's more acceptable. Even on those, though, I don't really ask them out - I just try to start conversation. It never lasts long. I've never asked a girl out in person, too shy. I asked one girl out on Facebook by saying, "maybe we should hang out sometime." She kinda likes me and we have a little bit of history. She hasn't responded, though. Another time I messaged her she responded months later.