A few weeks ago I was sort of following my niece around as she ran the Frederick marathon. At one point I was letting her run on while I rode across the street to a bit of a grassy patch where a friend of ours and two unknown to me people were standing cheering her on. I unclipped my one foot and then road up onto the grass which looked pretty smooth. Well the jarring of hitting the grass clipped me back in and then my bike came to a stop. I yelled out something like "SAVE ME" and luckily, unbeknownst to me, the two other people were cyclists and knew exactly what had happened. Both reached out and grabbed the handlebars and one said - the rough terrain clipped you back in, didn't it?

Moral is = in that instance, don't hover the foot over the pedal, you may find yourself clipped back in by something other than your own power.