Using this other guys method, do this for some fun:
1. Walk in any direction.
2. Press r (that's my bind for sit) right after you stopped walking.
3. If it worked, you should be walking without moving.
4. Next: Hold crouch.
5: You should be humping the ground without moving!
6. Next: Hold crouch and move in any direction.
7. If that worked, you will be crawling 'round without moving your body.