A childhood belief about physics

My sisters once told me that if you tripped, and then had something sudden happen to attract your attention, you would float. They told me that this was because we are so convinced that the Laws of Gravity are true that therefore they work. But when you are suddenly distracted, you forget about the Laws of Gravity and thus you float. Lets just say that jumping off of stools and ladders and having your sisters throw things at you is not a good idea...
(I believed this for several days until my Dad told me that they got it from some books by Douglas Adams.)