I've learned this when I studied Aiki-do, and use it till today when I meditate,
in order to quiet the monkey mind:

As you inhale, imagine a little red string enters your nose, it travels up to your lobe, around the head, then down the neck and spine, comes around and up the belly as you begin to exhale, past the chest and out of the mouth.

This sensory illusion, that you can repeat with each breath, keeps you 'in the moment', feeling your being and not thinking of anything else.

Also, Zen humor is good stuff :) Always brings you back to simplicity.