A fart when one's ass-crack is caked with mustard, preferably spicy brown. Similar to the musket shot, yet no smokey cloud is produced. Only clumps of fine mustard.
Patrick was marinating in his own scent when he bent over and plopped out a spicy brown mustard shot on Charboneau's chest.
by Hansellout November 9, 2007
When someone is so sure of their answer, they are willing to drink a shot glass full of mustard if they are incorrect. Usually used to overrule a friend or teammate's answer to a trivia question.
Roscoe was Mustard Shot Positive that the answer to the trivia question was "November Rain". He ended up drinking 1.5 ounces of dijon.
by MKLynch May 11, 2011