A generic insulting noun, coined by Butthead of MTV's Beavis and Butthead.
While they were watching the premier of GWAR's "Saddam a Go-Go" video, Beavis got in Butthead's line of view of the TV. Butthead shouted "Move it, fartknocker!"
noun: refering to the knuckle on your finger that, when inserted into the rectum of your sexual partner will cause them to expel gas around your finger and out their ass
dude check this out!!!! Got it in Sherry all the way up to here before I hit the fartknuckle!!!