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 June 5, 2011
Get the Mustard Shot Positivemug.