Wow, that's a pretty extreme example. And have you ever done it? What usually happens then? I can't imagine getting nervous texting a friend. I can understand being a bit iffy about approaching strangers, but friends or non-romantic situations, that must be pretty tough.
I have asked a guy out once. We went out once but I didn't really like him all that much. (I think that might be the reason I was able to confront him since there wasn't a whole lot at stake) I once kissed a guy without him initiating it. But he was a friend and we were having a slightly drunken cotton candy eating competition, so I couldn't help it. Other than that, nothing.
Generally I just get really nervous, kind of like I would when I have to give a presentation or do a really important exam. When I get nervous, I try to get out of the situation. I feel that it's not important enough

It's gotten a lot better since my Prometheus camp last summer. People tell me I'm more lively and comfortable in social situations.
I don't really think about it that much. I'm comfortable by myself or with close friends, anyway, and I don't usually feel a need to get to know new people. And again, if people approach me first, it's easier for me.