It's when you're sitting on the
edge of a Lake and you look to your right and see a
small Canoe and you can almost see that there is a hole in the bottom of it somewhere but you're not too worried because it's obviously not fully submerged so you
clean out the dirt and get into it without paddles, somehow make it to the middle of the Lake and then start to sink and panic because you're not in a Lake but in a shark pond.