snaf-tache
Also known as the Dirty Sanchez, this trick explains the recoil reflex of any adult when you try to put your finger underneath their nose. It involves sticking your finger up your arse, asking your victim to sniff your finger, waiting until they tell you it smells of shit, then wiping it across their upper lip. How far you stick your finger up your arse is entirely your own business.
written by Ja*es*Will*rton, approved by Log

Also a good trick for getting a pint of real ale changed; simply offer your pint to the barman to smell, having placed your finger up your arse. Offer him to smell the beer with your finger under his nose... a change of beer and a profuse apology. Resist the temptation to complete the snaf-tache.
written by Jo* Bly*h, approved by Log