How to complete the "humiliate an enemy" - field order in COD Ghosts

The Humiliate the next enemy you kill field order in Call of Duty Ghosts had me puzzled at first-but after a little "accident" with an enemy player I figured it out- its the good old "tea bag" or teabag or for female players often kalled "twat squat" or "clam slam" (pardon my language!). It simply sitting down on your enemy (use the crouch move) after you killed him-or her....

Why the makers feel it necessary to include this I wont question here.....