Pulling a William indicates that you have royally screwed up. Somehow, despite every possible odd, you managed to make the impossible and incomprehensible existent. Pulling a William also involves the "William Puller" to laugh maniacally after committing their act.
William Puller: *tries to build a house, but accidentally builds time machine operated by a rat with a lightsaber for a tail*
An individual who must fart but is reluctant to do so, therefore tries to clench the sphincter in order to "bite" the fart off into smaller, less noticeable mini-farts.
The fart biter was desperately trying to escape the public eye so he could ease his smelly problem.