The word poop meaning the rearmost and highest deck of a ship is derived from the latin word ‘puppis’. It is part of a large constellation called Argo Navis an represents the largest part of the Argo from when Jason’s legendary ship was split into three parts. When the rear of a ship was overcome by a large wave it would often cause the vessel to slew around and present her broadside to the wind, thus becoming overwhelmed by the sea. The ship was said to have been pooped. Hence the modern use of the word to mean exhausted.