"Prognosis: Negative" - the film Elaine wants to see with Jerry, is also the name of an unproduced screenplay Larry David wrote in which the main character wrongly assumes a negative medical prognosis is a bad thing.
Which must have also spurred this one:
GEORGE: This is George Costanza, I'm calling for my test results. Negative? Oh, my God. WHY! WHY! WHY? What? What? Negative is good?