Strange thing happened on the way to work

It happened to a buddy of mine when we were kids. We were out trail riding on our snowmobiles when I heard a loud bang. I looked behind me and he was just sitting on his sled in the middle of the trail with a "what the hell was that" look on his face. I went back to see what was going on and found a quarter size hole in the cowling of his sled. I had a spare plug on me so I put it in and away we went