Angus, one of our cats, HAD intended to leap from the top of my computer desk to the tall shelving unit 2 1/2 feet away.

The paperwork he was standing on, instead redistributed most of his energy by flying backwards towards the door and he barely made the edge of the unit. He scrabbled at that for a moment, then fell headfirst into the box of scrap paper. As he climbed out, his sister ran across the room and attacked him - presumably for waking her up. Not his day. He should have read up on Newton's laws before making his leap.