The frankly
disturbing act of inserting one end of a length of hosepipe
up your anus, placing the other end into a drink, then expelling your fart through said pipe. The result is the formation of a methane infused beverage as the gas bubbles through the drink. The drink should then be enthusiastically guzzled by yourself / lover / friend / victim.
See also Stealth - Fartneken where you do this to an unbeknown recipient who will wonder why you are laughing as they down their 'fruity elixir'.
The discipline has also given rise to several sub genres
according to odour, volume, bubble volume etc.