Some friends and I went out to Vail one year. It was my third time on skis, first time on a mountain out West. I'd freaked out earlier in the day on my ski skates because I just wasn't experienced on them enough to know how to turn. Everyone kept telling me, "Oh, it's just like skating. You won't have a problem." Except I did. Despite this, my friends somehow talked me in to going ski biking. At night.
On the first run, my headlamp died, so I couldn't really see where I was going. I just did the best I could to keep up with my friends. Got a new headlamp when we got back to the top for the second run. However, it seemed our guide must have had a hot date that night, because she couldn't be bothered to wait for us at the top. She just barked out a few quick directions, disappeared around the lift hut, and left us to figure out where she'd gone. A group of us followed what we thought she'd said, but ended up on an icy black diamond trail right under the lift. I lost control of the bike and was headed towards the trees. I just threw the bike away from me, went limp, and let myself skid down the slope.
Fortunately, a few of my friends were right there with me. They picked me up, found the bike, checked for anything broken, and then one of them who had a bit more familiarity with the mountain guided us back to where he thought the guide would be. Sure enough, we eventually caught up with her, and her lack of concern was astounding. She later accused us of having been drinking (which we hadn't) and going down that trail on purpose.
Needless to say, I now have a fear of speed and steep trails which I'm working very hard to overcome if I'm going to get anywhere with this sport.