Last weekend, I tripped and fell onto my front side on a steep trail, with my head pointing downhill. At first, I was pretty relaxed about it. It was a bit icy, but I had a lot of contact on the ground. Surely, I thought, I would come to a stop soon enough.
However, about ten yards down, I realized I was actually picking up speed! My skis were still attached to my feet, uphill, but they sure were not contributing any friction. The poles were under me. Time to panic.
Out of desperation, I stuck both my thumbs into the snow. They were the only appendages over which I had any control. And, the snow had just softened enough that it actually worked! Well, another couple of yards later.
Total skiddage: 20+ yards...
Not anything I would recommend... more like a funny story. Thought of this thread immediately.