It's a Vedic thing. The Vikings practiced it also. It's done in Hindu tradition in the mornings - basically to suck water into your nostrils out of your hand, then blow the water and gunk out. You do it 2 or 3 times. You don't do it deeply into all of your nasal cavities - It's just a small one. I learned to do the full Vedic practice in Yoga School where you use a little 'jug' to actually pour water in... but then you need to do a bunch of asanas (yogic positions) to make sure your nose is fully clear of water again or you can have problems. Do the mini nose cleanse... you'll be fine : )