Oh many many times, as Im a very clumsy person. I was at a gym a few weeks ago, and I was on a treadmill. For some reason, I thought If I stopped nothing would really happen, either that or I just FORGOT I was on a treadmill. I stopped to pick up something, and went flying. The whole gym started laughing, and so did I. I went the gym again today, and went to get on the, coincedentally, same treadmill, and tripped ONTO it ;___;

There have been many other times like this, though, when Ive falled over nothing at all, and been adament there was a stone when I was just lieing to myself.