This achievement takes place on Mission 8: Ratte Factory.
To get this achievement, work you way through the beginning of the level, and kill a few enemies near the large green bridges that span across the middle of the map.
After that, make sure you shoot the explosive barrel on the middle bridge, which will cause some of the beams to break, and leave you an open piece of the bridge. Pick up a body, walk to the bridge, and throw it (Y) through the hole created by the explosion.
Achievement Unlocked.