To earn this achievement, you'll need to throw a body where there are alligators in the water. The easiest place to do this is at the very beginning of the game, when you jump off the boat to fight the Hatians. Once on the dock, go right and you'll see a lone guy standing on the end of the dock. When you kill him, just pick up his body and drop it directly in the water for the achievement. Here is a video [credit to PowerPyx] for more help: